Another Centurys Episode 2, a mecha action game, gives players the Amon Duule "Stack", a red unit from Heavy Metal L Gaim. In both the game and the series, the unit is technically a flawed and defective piece of junk, despite having a stupid powerful beam cannon that would make Wing Gundam cry. However, after some minor upgrades and using the unit for a little while, the player can upgrade it into its true form: the L-Gaim Mk. II, the most ridiculously powerful unit that the good guys get in the L-Gaim series, and a very good power unit in ACE 2.
The game starts you off with a gimped version of the legendary Vampire Killer whip, and it is the weakest whip in the game. However, if you defeat its "memory" (AKA Richter Belmont) in a Bonus Boss battle, you unlock its true power and turn it into the most powerful whip in the game.
The game also features two gag sub-weapons: the pie and paper airplane. They're functionally useless until you level them up to max level, when they suddenly become some of the most powerful subweapons in the game (and interestingly, are particularly useful in unlocking the full potential of the Vampire Killer).
Castlevania: Symphony of the Night gives us the Muramasa. A middling two-handed weapon whose obvious benefit is that it provides an automatic heal whenever an enemy bleeds on Alucard. Less obviously, the sword actually grows in power over time as it absorbs blood... the only limit to its power is the calculation algorithm of the game. However, in the time of actual gameplay, it's far easier to acquire a number of other game breaking weapons before leveling Muramasa to the point of it being of any real value. Players who do manage to power up Muramasa tend to just take advantage of a turbo controller in a specific location while leaving the game running over night.
Refuse to trade away your wimpy initial weapon until the near-end of the game, and you'll be able to upgrade it to the almighty Spur. This is partially a reward for honesty, since said wimpy initial weapon technically doesn't belong to you.
The Bubbler is another example. At level 1, it's similar to the above-mentioned wimpy initial weapon, but slightly less useful. At Level 2, it makes a decent substitute for the Machine Gun — a weapon you can't get if you're going for the Spur. At level 3, it fires a cloud of bubbles as long as you hold down the fire button, which start popping rapidly and firing lightning bolts once you've built up enough... and once you release the fire button, they all pop and fire their lightning bolts at once. This is roughly as potent and deadly as it sounds.
In The Godfather: The Game, the shotgun is a bit like this. With a two-shot clip size and 12 rounds to spare, 24 at the second level, it's outclassed even in assault situations by the Magnum with six rounds per clip and 36 rounds (60 at level 2) to spare without sacrificing much power at all. Once you throw $450,000 at the right black market merchant to upgrade it to the level 3 "Street Sweeper", it goes up to ten rounds a clip and 100 rounds to spare with an automatic action, compared to the Magnum's level 3 "Python" with 8-80 and semiauto. Unless you are feeling the need to be stylish or are somehow running low, the shotgun is now the way to go.
Several weapons in Onimusha: Dawn of Dreams are like this, one of which is the Onimaru, a katana for Jubei. It can be dropped by an early-game enemy, but its attack power is much lower than the other weapons you can get for her at that point. Level it up enough and it gains Attack +100, Normal Attacks +40% (basic physical combos get a major boost to attack power), and Generate Attack Wave (which shoots energy waves with every attack made with the weapon, thus increasing its range). Jubei will then be able to shred through nearly everything you come across and continues to be useful even in the second disc.
The bow and arrow in Castle Crashers. Initially, the weapon fires arrows at an angle and at a very slow speed. Increase your character's Agility stat, however, and the angle lessens until it fires straight ahead and arrow speed shoots up considerably. With a high enough Agility, you can even juggle enemies with the bow!
A player may find the Cursed Sword. As the name suggests, it's cursed; every time the player tries to swing it, it damages the Player Character. However, if the sword is swung often enough, it becomes the most powerful weapon in the game, outmatched only by weapons that are specifically designed to kill certain types of enemies.
There's also the other Cursed Sword, which randomly can't be swung and isn't very powerful. Pick it up 8 times with a cleric, and it becomes the Holy Avenger, the second most powerful weapon in the game.
If you time it correctly, you can interrupt the "knock-back" animation (and the damage!) from the curse by either jumping and swinging right before landing, or having someone else cast a targeted spell (like Cure Light Wounds, or Striking) on the Sword swinger. Cursed Sword 2 is much easier; have the Cleric (try to) pick it up enough times.
This describes Phoenix Wright from Marvel vs. Capcom 3 in a nutshell. He starts with poor mobility, weak normal attacks, and a lack of moves in general. Collect evidence and put him in Trial Mode, however, and he gains access to a variety of projectile attacks and much better moves. And if you can get him in Turnabout Mode, he becomes one of the strongest characters in the game, doing immense damage with all of his attacks, having invincibility with some of his moves, and gaining access to one of the best level 3 Hyper Combos in the game - which is the single strongest attack in the game, no less.
Pucci's moveset in JoJo's Bizarre Adventure: All Star Battle is based entirely on this. He first starts the match with his stand Whitesnake, which is rather versatile but underpowered. By speaking all 14 of Dio's secret words to Green Baby, his stand permanently transforms into C-Moon and gives him several new moves, including his GHA which allows him to further evolve his stand into Made in Heaven. Johnny also fits to a lesser extent, since he gains more moves the further Tusk evolves throughout the match.
In the sixth game, the bow moveset shared by Sun Shangxiang and Yue Ying initially seemed dismaying - "They took two of the coolest women in the game and gave them a useless weapon!" However, once you level up that bow and arrow, it's a monster because you can spray tons of arrows into the crowd at once. It's also a bit of a Game Breaker in that you can snipe from a faraway enough distance that the computer AI generals don't realize they should block your attack.
In Dynasty Warriors Online, it's actually part of the mechanics. No weapon ever starts out at full power in the first place. You have to temper weapons so they have better stats. This trope comes in, however, in that tempering only has a limited effect on the stats based on the weapon. If you grind a weapon, you have to use it so many times, you can change the stat spread on a weapon. On some weapons this is needless. On others, like the tonfa, this turns what is otherwise a horribly stated weapon into a competent one, with good combos as well.
The Crystal/Big Star weapons in Warriors Orochi 3. Initially they start with low attack power (usually 9 or 10), but at max proficiency they gain a plus 54 attack increase, making them the most powerful weapons in the game, except for a select few 4-star weapons reserved for extremely Bad Ass characters.
In the X-Box remake of Ninja Gaiden, the wooden sword is easily the most useless weapon in the game, and takes the most time/money to upgrade fully... but once you do, it becomes the most powerful weapon in the game: the Unlabored Flawlessness.
In Ratchet & Clank: Up Your Arsenal, many of the weapons will be crap to start with, but after an upgrade or two, will become massively awesome. Particularly the Holo-Shield Glove. V1: blocks a few projectiles before it shorts out, and serves no secondary purpose. In a word: useless. V2: blocks more damage, and sucks the very lifeforce from your enemies to heal you. In a word: awesome.
Tails, specifically Sonic 3 & Knuckles: in both Sonic 2 and Sonic 3 without the S&K lock-on, getting all seven Chaos Emeralds didn't do squat for Tails other than rewarding the player with the Good Ending, unlike Sonic. Oh, but that changed in S3&K: getting all 14 Chaos Emeralds (seven in the Sonic 3 portion and seven in the Sonic & Knuckles portion) nets Tails' Super Mode, complete with super transformation sequence, glowing body, and the best part: four birds (called Flickies) that home in on enemies and deal damage to them — all Tails has to do is just stand and burn rings for energy. Oh, and the birds can damage almost any boss in the game. The bosses things they aren't good for are one of the bosses in Death Eggnote which can only be damaged by its own bombs, and the miniboss of Sandopolis Zonenote which must sink in some quicksand in the left half of the arena, but the birds don't know that and knock the boss all over the place.
An example from Sonic Adventure 2, the Mystic Melody power-up. On your first playthrough it will seem useless, and no characters can get it unless they go back on levels to find it (for some it's easy, for others you can't get it until the last level). Then, when you finally HAVE Mystic Melody, you can use the power with small, slightly-hidden temples. The Melody can do everything from open portals to cause rings to magically appear, which you can use as shortcuts to later parts of a stage or pathways to other powerups...basically, an in-game cheat item.
The Farmer class, whose special powers are of very limited use compared to those of other classes. The exception is their final power, gained at level 50, which grants 30% resistance to all corrupting effects - possibly the best power in the game.
Necromancers are generally played as wizards whose class power drains their magic, but when they reach level 50 they can come back from the dead.
Just getting Mindcrafters through the game relies upon this. They start unable to learn spells, no offensive abilities, awful equipment and may or may not have a damaging magic wand. If they reach level 6, they finally gain Mind Blast. That takes the heat off, but you're still unable to use your powers on undead and unlife, which is why levelling up still further to lvl. 15 is the make-or-break point, as you learn Telekinetic Blast: a physical attack that strikes remotely and never misses.
The Tourist character class. They start with a handful of darts for a weapon, a hawaiian shirt for armour, and a jumble of seemingly-useless tools. Only an experienced player would know that in the endgame, an enchanted cotton shirt is one of those things everyone wants but are normally so rare that most of the time they're only obtainable via Wishing (in other words, Tourists get a free wish for starting with the shirt). They can acquire the Platinum Yendorian Express Card, one of the more powerful artifacts in the game. They also have the greatest selection of weapon skills of any class, and can become proficient in every weapon but clubs (which aren't a good choice for a weapon anyway).
Less extreme but still eligible is the Wizard class. It starts with a quarterstaff for a weapon and a piddly little Force Bolt for offense (and one random other spell). By endgame, Wizard is by far the most powerful class in the game. Area effect magic, infinite death spells, instantly mapping dungeon levels, instantly identifying unknown items, teleporting at will... all with nigh-infinite MP because of their quest artifact. Oh, and their first sacrifice gift allows for unlimited, instant, semi-permanent Elbereth. And zaps enemies with status ailments. And blocks curses. And is powerful enough to let Wizards play melee, if they so choose. Did I mention they get bonuses to Magic Marker use, hungerless casting, self-healing, no-items-needed levitation, Very Fast speed... you get the picture.
Initially, Isaac starts the game with no usable items or accessories to give him a bonus at the start. After beating the game a certain number of times and meeting certain criteria, however, Isaac begins with a D6 which will allow him to reroll unfavorable item drops for a chance at something better, giving him better scope than the other characters for customized powerbuilds.
The cube of meat item will initially only act as a shield, blocking attacks against Isaac and inflicting collision damage on enemies. Finding two will allow it to attack enemies in conjuntion with Isaac's tear attacks, three will turn it into a Meat Boy pet who will seek and destroy enemies, and four will up meat boy's size and damage.
The Carnelian (Crystal Type B) suffers from this. You start out with no weapons, no drones, a three-Crystal crew, and a four-man teleport. Getting through the first sector or two requires more than a little bit of luck, since you have no way of destroying Rebel drones unless you sacrifice a crewmember, which is a spectacularly dumb thing to do. However, if you can keep it flying long enough to get some more crew and some backup weapons to shore up your offense, then it's far and away one of the most powerful ships in the game.
The Basilisk (Mantis Type B) also suffers from this, but not as badly as the Carnelian. You start out with two Mantises, two layers of shields, and a Defense Drone and Boarding Drone. While you're better equipped to shrug off enemy attacks, you have to leave your ship on autopilot while you send your Mantises over to fight. Also, Mantises naturally have horribly slow repairing speeds, meaning it's nigh-impossible to get a system running again in the thick of combat. Again, though, if you can get some additional crewmembers (preferably Engi to shore up your repair capacities) and some backup weapons, then you've got a powerhouse.
Numerous Pokemon in the Pokémon Mystery Dungeon series are like this, only getting tiny stat gains at lower levels, but suddenly getting huge gains after crossing a certain level threshold. For the most part, if a Pokemon seems bad initially, it's going to end up improving greatly sooner or later.
The Gold Sword in Azure Dreams is a pretty weak weapon that looks like Vendor Trash at first glance until you realize that it's the only sword that can't rust. Give it plenty of Red Sand and you have an extremely powerful weapon. The Trained Wand is similar but much harder to find.
Aveyond: Lars has annoyingly low heath points and very poor melee damage, but level him up all the way to 99 and he is the most powerful magic user in the game.
Pecoros (Or Peco) from Breath of Fire III is introduced fairly late in the game, and at level 1 to boot, meaning that most players ignore him and focus on their A team, however this also means that he arrives at a time where most of the game's masters, who can modify stat growth at level up, are available, meaning that he can be heavily customised as he levels.
Breath of Fire IV has a New Game+ mode in which you can obtain a rusted sword. It's not a particularly impressive weapon, but if you kill 1000 enemies with it, it gets transformed into a significantly more powerful weapon, the Slayer.
Pip starts off as a cute little bundle of fluff and is as powerful as it sounds. You can evolve him using a not too complex, but tedious method into an Archangel, Archdevil, or Holy Beast form. They are also as powerful as they sound.
The Healers in the Sega Game Gear title Crystal Warriors resemble this trope in that they are remarkably weak in melee combat. If you manage to get one to level 9 somehow, though, they suddenly turn into unstoppable killing machines. To put this in perspective: a level 9 Healer has 95 HP, 85 Attack and 80 Defense. By comparison, the game's Final Boss has 98 HP, 97 Attack and 12 Defense.
Xiao from Dark Cloud is ridiculously weak when she joins your party. Her sole use seems to be getting past the occasional obstacle, and most players will only pull her out for those, ignoring her otherwise. And then comes a level where you have to play as her, and only her. If you then decide to level Xiao up a bit by taking her through some of the earlier stages, you will learn that (a) Xiao isn't actually that much weaker than Toan was at the same level; (b), her weapon is really fast; and (c), having a ranged attack is useful when facing monsters and (d), you can get her a slingshot that can steal items upon successful hit. There are also enemies that you do not want to get anywhere near melee range, and enemies that cause your weapons to degrade faster. Xiao is immune to all of these, given her weapon is ranged.
Dark Souls: The Soul of Sif can be used to craft the Cursed Greatsword of Artorias, a fairly mediocre weapon whose only real advantage is being able to attack ghosts (and there are better ways to do that). However, if you combine it with the utterly useless Broken Straight Sword +10 weapon, then it creates the non-cursed version of the sword, which gets the best Holy modifier in the game and scales very well with stats. The Holy modifier has the bonus of preventing skeleton enemies from re-forming once defeated.
The club, starting weapon of the Deprived class. It might be unimpressive compared to a nice shiny sword, but it has some of the best stat scaling in the game.
In Disgaea: Hour of Darkness, Angel Trainee Flonne only levels up well with a staff but learns no spells beyond her three special attacks, making her almost entirely useless... unless the gamer discovers that the apprentice system lets her learn other classes' spells, in which case she can effectively be turned into a ridiculously powerful tank-mage with an attack range that would make gunners weep.
Then subverted when Majins become available (through a good bit of Level Grinding); they have 110%/120% in aptitude in all statistics and "S" skill growth in all weapons, making the story characters, with their flat 100% aptitude (otherwise powerful among generics) and mediocre skill growths, completely irrelevant. (In an amusing case of game design whiplash, later games in the series tone down the Majin to such a degree that they're rather limited right out of the box.)
Super-Robot Thursday, being a robot, cannot reincarnate and gain all the juicy stat bonuses it imparts; he makes up for this with 150% aptitude in most statistics and ability to steal stats, so give him some time and he can be a very powerful character. However, his lack of skills and inability to use a staff to enhance any spells he may learn from pupils relegates him to a distant second behind a properly levelled and transmigrated Divine Majin.
DragonBall Kai: Attack of the Saiyans has Gohan, who like his anime counterpart at that point in the series is a near useless runt, only gaining one point per stat whenever you level up, compared to the other characters who all have one or two stats that get extra points. That all changes once you get to level 35, where not only does Gohan start gaining two to three points extra on all his stats, but it makes him the single character in the game who can completely outdo Goku.
Day Of The Idea: The Soroi uniform for Tomoko, it's very crappy and you cannot appraise it unless you have all 8 parts of the set. All of the equipment is scattered around the world.
The Tanuki has rather crummy stats, and hides if injured and can easily be replaced by another pet, but when you find the Symbol of Courage, it becomes a more useful ally.
In Dragon Quest III, the most useless class, the Jester, can be upgraded to the most powerful, the Sage. For anyone else this requires a unique item that can only be used once.
Dragon Quest V allows the player to recruit monsters as party members. One of the first monsters the player is likely to recruit is the basic, run-of-the-mill Slime, with a whooping 8 hit points and next to no attack power. By the time the Slime reaches level 20, it has more hit points than a similarly leveled main character, and is outclassed in attack by only the main character himself when properly equipped. Combined with learning an absolutely devastating spell at level 50, the slime is easily one of the best monsters in the game. And if you are lucky enough to be able to catch a Metal Slime, they are even better!
Slimes from Dragon Quest Monsters fit the trope pretty handily. They're the classic DQ monster, you see a billion of them in every game, and they're pretty mediocre... but if you level them up high enough, they learn the MegaMagic spell. What does MegaMagic do, you ask? Why, it's one of the most powerful moves in the game, dumping every last one of your remaining magic points into a super-powerful magical explosion that absolutely nothing in the entire game, including those damned Metal Slimes and their upgraded versions, is immune to.
The game has a sword called Iron Butterfly, that starts off very weak and stays weak until Lv. 4, where it becomes super-strong and has a powerful magic attack. However, to even level it up to 4 requires a LOT of patience due to how much experience it needs.
It also has a sword that deliberately inverts it. Beginning with very high attack power, and growing weaker with each level, its own level 4 being virtually useless.
The first game had Hymir's Finger, a totally-not-the-Dragonslayer broadsword as tall as you are, that hits like a mountain (and just as slow, too, so enemies will often hack you before you can swing). But when you get it up to level 4...
Claves is, when first encountered, extremely weak, with slow attacks that don't do much damage, and unimpressive specials, Presumably this is so you don't waste any time leveling her up, because she dies almost as soon as you meet her. If you go through the game's Bonus Dungeon, she can be re-recruited and leveled up properly, eventually becoming one of the game's strongest characters, placing first or second in every stat, and having some seriously powerful moves. But since she rejoins at the same level as she first left, and thus probably 30 or so levels behind, most people never find that out. The drawback to this is that said bonus dungeon can only be accessed once you defeat the second to last boss, and open a portal that would literally take you right to the final battle.
There's also Frederic, who is noticeably weaker than many of the other characters owing to a high magic stat but a poor attack stat. Furthermore, most of his special moves are weak, up until roughly level 60, when he unlocks Phantom Pain, the best damage-dealing skill in the game, capable of inflicting upwards of 400,000 damage with the proper equipment.
Jazz in the 360 version. He is at every point in the game inferior to all other characters available. At the end, however, he gets a next to final weapon with an ability called Burst. Burst doubles the power of attacks in exchange for defense. He's the only one with a REALLY strong burst weapon, and the lack of a third burst item means he is the only one who can use burst without one in your three man team. He already did massive damage but other characters had him outsped by far and thus got in more damage than him. In the PS3 version there is now a third burst item and a new character that's a borderline gamebreaker. The existence of a third burst item greatly decrease his value in favor of everyone else.
Evergrace: Zul's Toy is a toy hammer which becomes a Lethal Joke Item (and the most powerful weapon, capable of defeating the final boss in about two hits) when you upgrade it twice.
Fullmetal Alchemist: Curse of the Crimson Elixir: The flare does little to no damage and is only good for stunning enemies....but if you can level Edward to 99, he can transmute the flare into an absolutely devastating smart bomb that wrecks everything in range.
In the popular RPG Maker 2000 Affectionate Parody game Jays Journey, one of the hidden party members is... a slime. As in, the quintessential weak RPG monster, and indeed, the slime's stats are pathetic. ...at first. If you stick with it long enough to get it up to Level 50 and find the hidden "Slime Medal" item, all of its stats are maxed out, and it has a set of the most powerful spells in the game as well.
In the original Kingdom Hearts (and the HD remake) Sora can be a little like this - depending on the choices you make in the early dialogues, you can have an experience curve that starts off painfully slow, but, somewhere around level 45, overtakes the other experience curves and ends up higher level by the time you reach the final boss around level 60, and can reach the level cap sooner too.
Weebos in Magi-Nation. One of the first Dream Creatures you can get, it starts out at level one, with the sole ability to heal. BUT, and this is a huge gigantic but, if you raise it to level NINETY, it learns the immensely powerful move Wreck, which is shared only by Ormaggon, the subject of That One Sidequest.
In a mix between the Elite Tweak and this, Aaron of Lunar Knights starts off woefully underpowered (made worse by the fact that he can't fire without a Terrennial, and the first part of his chapter is a forced stealth segment because of this flaw). On the higher difficulties, however, further play as Lucian requires maxing your levels or having godly guard reflexes, as the enemies' damage output continues to rise, not to mention the direct-player-induced 999 damage limit. This ultimately puts Aaron on point, where his Solar Guns, coupled with energy levels on par with freakin' Naruto, help mitigate the risk of having to get close to such deadly attacks.
Zach has one attack skill called sinstrike which deals armor piercing damage based on Zach's kill total. It seems utterly useless until you put some effort into kill grinding him, and after a few hours, which isn't too long for a MARDEK player, it becomes the most devastating attack in the game. That is, unless the enemey is immune to dark damage...
Elwyen also qualifies. She starts out at around level 10 (when most of your character levels are in the mid-late teens) with one of the lowest HP counts of any playable character, and a small number of somewhat counterintuitive abilities. Take the time to level her up and teach her the right skills, though, and she ends up with the strongest defensive reaction skill in the game, a decent party heal, powerful party buffs in a series where buff spells are usually mediocre to crappy, and the most effective attack against several dodging-focused Demonic Spiders.
Ambrosia. Unless you want to count her Useless Useful Spell Trigrams (which can end up healing the target as part of random chance and otherwise is more or less a percentage effect), and her totally useless spell Predict, she has effectively no abilities for the first quarter of the game. Then she gets a holy spell, a defense spell, a slow, and a death spell (still in the Useless Useful Spell territory). About the fifth spell, she starts getting various damaging effects. By the way, none of her spells use magic, so if you can bear the torture of waiting for proper plot events, she suddenly becomes a One Man Party.
Tamashii, her daughter, is even more this, having bad stats as well until you get near level 99, when they're the best in the game. You also have to level up an evolving weapon to max out her weapon damage.
T260G's original body in SaGa Frontier. It has stats of only 5 in every area, and the only piece of equipment it comes with is a piece of weak armor, while the other bodies you can switch to have a wide variety of extra gadgets, like lasers, repair kits, missiles, tougher armor, and more. However, all of these things take up equipment slots, and mecs like T260G gain stats by equipping items rather than leveling up; in his original body, he has seven slots free for stat-boosting equipment (as opposed to only 4 or 5 in any other body), so it has the potential to be the strongest of all in the late game.
In Secret of Evermore, almost every damaging alchemical formula could be a sort of magikarp power, in that they almost all suck until you've used them a couple of dozen times, at which point the only thing stopping your rampage across the ages is the state of your wallet (as you need to money to buy reagents.)
In Shin Megami Tensei III: Nocturne, by keeping the very first demon you can recruit (the Pixie) in your party for the entire game (she becomes rapidly outclassed very quickly)note Fusing her with other demons is okay; her "DNA" carries over in everything but a sacrifice fusion where she or her "descendent" is the sacrifice and then presenting her to a door in the final level of the Labyrinth of Amala, she transforms into a Lv.80 juggernaut with 30s in every ability score and some of the best spells in the game. Also note that that particular species of demon is an example of Magikarp Power to begin with, as leveling one up when your main character is around level 50 enables her to evolve into one of the best Night demons, Queen Mab.
Odin is pretty unremarkable at first (well, by the standards of a level 63 persona, anyway...) but a bit of grinding gets him Thunder Reign, an "extreme" tier Lightning spell. If that doesn't kill the enemy outright, it's also guaranteed to put them in Shocked status, meaning any subsequent physical attacks against them will critical. Level Odin a little more, and he gets Spell Mastery, which cuts his SP costs in half.
Daisoujou hardly seems worth the effort to fuse... until you realize it's the only way to get Samsara, the strongest light spell in the game, which has a high chance of delivering an instant KO to all enemies.
Junpei starts off as a decent tank, but quickly falls out of favor when nearly every boss uses his weakness element. Keep him leveled up, though, and he becomes a force to be reckoned with come endgame.
In Persona 4, Chie starts as a fairly basic attacker with access to weak Ice magic, but quickly falls behind compared to the rest of the party. Keep her levelled though, and by endgame she'll have some INCREDIBLE skills, including Power Charge and God Hand. Plus there's the fact that if you get her Social Link to level 3, her Galactic Punt follow-up attack can oneshot any non-boss enemy. Including minibosses. The Golden gives her S.Link Dragon Hustle, a full party Heat Riser, when maxed.
Atsuro of Devil Survivor is primarily a physical attacker. Early on he is relatively useless due to magic being overwhelmingly more useful and powerful thanks to the magic stat governing MP, magic attack, and magic defense and being able to exploit elemental weaknesses. There are very few enemies with a weakness to Physical attacks. That some of the more powerful late-game enemies have passives that reduce, drain, negate, or reflect physical attacks does not help matters. But Atsuro redeems himself at later levels too. Provided you've cracked them (and you should), skills like Full Might, Attack All, Pierce, and Phys Jump/Rise will turn Atsuro into a Physical God that can bypass all defenses except Phys Repel, strike all enemies at once, and always get critical hits (which can steal Extra Turns from enemies). If necessary, give Atsuro Phy Repel to ensure that he doesn't get hurt from rebounded attacks. His high Vitality also means that he can make good use of powerful hp-dependent attacks such as Deathbound and Hasseohappa.
Domingo, a jellyfish spellcaster whom you got late in the game with 1 low level spell. He eventually was able to spam cast the strongest ice magic in the game. He also gains such absurdly high HP, MP, and defense that at higher levels he literally shrugs off any enemy attacks, making even the game's resident tankGuntz blush in envy. And he can fly. And the fact that he has very high priority from the game's AI targeting system makes him break the game.
Arthur starts off very weak and doesn't learn any spells despite having Mana for several levels. But once he reaches about level 20 unpromoted or level 12 promoted, his stats suddenly skyrocket and he'll learn the powerful Bolt spell. He's one of the best units towards the end of the game.
Adam from the first game is an extreme case. He has the potential to be an excellent offensive unit. Unfortunately he joins you very late in the game at a laughably low level (Level 10 unpromoted) and is very slow, making him extremely difficult to level up.
Narsha in the Game Boy Advance remake zig-zags this. While she starts of quite weak at level one, you first get to play with her at the end of the first chapter. (When your characters aren't too far ahead), and she becomes quite useful due to her buffs. You get several more chances to level her and Zukia up, until they (and Mawlock) join the force, possibly close to the level of the rest of the Shining Force, and with enough time to use her. However, it takes a bit of babying in Narsha's first chapter for her to not get knocked out by the monsters, who are a little above her level.
Shining Force II has the turtle (named Kiwi by default) later evolved from a potent character with mediocre attack and low HP, but disproportionately effective defense, to a much more impressive-looking monster whose defense advantage didn't amount to a hill of beans against higher level enemies. Not a good choice for late-game, especially since his high defense does nothing against spells which all do a set amount of damage within a small variance.
In Shining Force III on the Saturn, Irene and particularly Cybel have awful HP, but persevering with them and allowing them to unlock their various specials allows them to become more effective in combat than even Dantares in the latter portions of the game.
Suikoden III: The Budehuc Castle characters, such as Thomas and Cecile, start out extremely puny (one of the game's first random encounter enemies is a boss in their chapter), and possess horrible skill growth (which normally implies a low cap on said skills), but with determination, their skills can be raised to extremely high levels, and their stat gains improve by leaps and bounds, turning them into some of the best late game characters.
Summon Night: Swordcraft Story 1 has a master blacksmith "tricking" you into smithing a ladle for him to cook with. You can use it as a weapon, but it breaks very easily and does pitiful damage. However, if you forge another ladle with 50 of each material type available and use Mystic Ore on it, you get a... burning ladle. Which still does low damage but has the highest durability in the game, meaning it's ideal for breaking other opponents' weapons without knocking them out; which instantly wins the duel for you and teaches you a new smithing recipe. You will want to fight all weapon-bearing bosses with this, really.
And to boot, if you dismantle it, you gain, instead of the common percentage of materials used initially, TWO Mystic Ores, a material that is often difficult to accumulate due to being grind-tedious to drop and luck-based to find the enemies which drop them. If you got no patience, and feel like burning through some money and/or surplus materials...
It is possible to obtain an item called a Mystery Egg. When used in battle this item does one of two things: If used by Princess Toadstool while wearing the B'tub Ring, it forms a heart and makes a pleasant ring. If used by anyone else or Princess Toadstool without the B'tub Ring, it fails to produce the heart and makes a buzz sound indicating failure. If the Princess produces enough hearts, the egg transforms into the potent Lamb's Lure, an item which can instantly kill any one non-boss character in the battle by turning it into a sheep. Use this enough times, and it becomes the Sheep Attack. It works like the Lamb's Lure, but affects all enemies in the battle. Unfortunately, you earn no XP or Coins from enemies defeated with either version.
Mario's Jump attack. For most players it will be completely overshadowed by the mighty Super Jump as soon as it becomes economical (i.e. you have plenty of Flower Points to spare). However, every time you use Jump (to a maximum of 125 times), it becomes permanently stronger. Eventually it is so useful as to be a Game Breaker, especially since it is still one of the cheapest moves in the game.
Klarth from Tales of Phantasia starts off as The Load, being a summoner with nothing to summon, meaning he's reduced to just hitting enemies with a book. It doesn't take long for him to get his first summon, though, and by the time you get the first four summons he's a force to be reckoned with.
The Devil's Arms from the same game are the weakest weapons in the game. After killing a large number of enemies (and defeating the Bonus Boss), though, they are easily the strongest weapons the characters can equip, to the point where they'll be doing 10,000 damage per hit. The concept has been replicated in the Tales games developed by Team Symphonia. They were called Catalyst Weapons in Tales of the Abyss and the Fell Arms in Tales of Vesperia. To unlock their power requires beating a very nasty secret boss. After that they power up by killing a large number of enemies.
In Valkyrie Profile's normal and easy modes, every character who joins you starts at an appropriate level for that point in the game. In hard mode, every character joins at level 1. Sound like a crippling disadvantage? Not when there are accessories that give extra skill points and maximum HP at each level up, you can equip both at once, and the difference they make over 30 levels or so is very signficiant. Bosses that, in Easy or Normal, require the use of the Auto-Revive or Last Chance Hit Point skills to even survive, Hard mode characters will be able to straight up tank.
The World Ends with You has Joshua, who's the only partner who can't block, only deals damage when his combo is complete (unlike the other partners, who actually land blows with each branch in the combo) and initially seems rather wimpy. However, he eventually gets the ability to levitate, in which mode he's much, much better at damage-dealing (including splash damage), hits with each button press and with enough hits on the same enemy before the finisher, hits every enemy for increased damage. Also, his most powerful special attack drops the moon on your foes and does at least 3 times as much damage as the strongest special attacks of the other 2 characters.
Secret of Mana: The Sprite's offensive magic starts out fairly weak, but if you spend the time to level it up, it reaches Game Breaker levels. Then there's the girl's magic: for a paltry 2 MP, Healing Water can restore 800+ HP to all members (you have a Cap of 999 for the Hero and 800 for the Girl and Sprite). That's forty-nine casts of full-party HP refill. Oh wait, you can also carry 4 Faerie Walnuts on you at any given time, so that's another 100 casts of that spell. The Sprite doesn't need faerie walnuts; it has MP-Drain which can totally drain most enemies when it is maxed out.
In Legend of Mana, many basic techniques are of little utility and some can be actively harmful at times. Spin can cause the main character to be disoriented, and Grapple often results in the character being squished by heavier enemies. These abilities must be used many times to unlock the powerful and devastating Special Techniques for each weapon.
Chu-Chu from Xenogears. Give her enough drives and she becomes the most powerful gear in the game. Of course, it takes a while to do it. Plus she's the only one who can heal gears in battle without burning fuel.
Velvet's Homing Attack from Odin Sphere, her claim to fame, isn't particularly useful, only hits one enemy, will usually fly off and hit a nearby projectile or item if it's the closest thing to her, and takes half her POW Meter off for each use. After enough levelling up, though, it can now hit multiple targets with enough force to One-Hit Kill the weaker enemies (including slimes) and carve huge chunks of HP out of the stronger ones, making it perfect for crowd control.
Several of the archetypes have this feature. Some types of Controllers, for instance, are fairly hapless at low levels when soloing but on reaching high enough levels (and with a selection of complementary powers) become unstoppable engines of destruction that can outdamage the dedicated damage-dealers.
Dominators are a very good example. Often considered underdogs, perceived as one of the two weakest archetypes in the game... at least until somebody discovered that, with some careful (and prohibitively expensive) build planning, one could stay in their "Mr. Hyde" mode without having to recharge it between uses. A "permadom" Dominator is easily one of the strongest characters in the game.
The (supposedly) lower-tier Agility heroes from Defense Of The Ancients have this. Starting out, not only is their health and damage disappointing, unlike Intelligence heroes or higher-tier Agility heroes they don't have good spells for burst damage, making life difficult. By avoiding the enemy's assassination attempts and building gold and levels, though, they eventually become One Man Armies who eat mooks and their former oppressors like so much popcorn.
Guild Wars: Mesmers. At their peak in the hands of a skilled player, Mesmers are hell on earth for enemies, due to the fact that the class's showcase style is turning an enemy's power against himself and making enemies die in a matter of seconds for no immediately obvious reason. However, in any campaign, it takes time for mesmers to find all the specialized skills they need to perform at peak efficiency, and even more time to get over the huge learning curve of the class-early mesmers, and unskilled players, are mildly annoying at best, and have minimal impact on anything.
Necromancers would fall under this catagory as well. Initially, they seem like one of the weakest classes in the game, only able to deal weak hits and very slowly drain an enemy's health bar, while the Necromancer himself takes damage like a newborn baby. However, once you hunt down some of their more useful skills and start capturing elites, they become extremely versatile and devastating in both PvP and PvE.
In the sequel, Mesmers again fall victim to this trope. Initially they are very off-putting. Most of the other classes have unique and useful class-exclusive mechanics, while the mesmer's only real power is to create very weak clones of himself, in addition to being a Squishy Wizard. Later on, with the proper skill setup and trait point distribution, they become absolute monsters capable of piling on damage in many different ways, often all at once, while creating mass confusion by pumping out identical copies of themselves capable of tanking and creating distractions, or exploding For Massive Damage.
In Pirates Of The Burning Sea, the Freetrader class is one of the weakest in the game at early to mid levels, having no decent specialised combat ships unlike the Naval Officer and Privateer classes. But once you reach max level, you get access to the Couronne Mastercraft Galleon, which is arguably the strongest single ship in the game. It possesses equal or greater firepower than the best warships that Naval Officers can sail, and its armor is much thicker and tougher. It also has the bonus of eight bow and stern cannons, making it quite deadly when approached from any angle, whereas almost all other ships in the game have only two bow and stern cannons.
Although it became easier eventually, alchemists/creators were slow to level unless you had a large amount of money, but once they get one particular skill, they can one or two hit most players.
Likewise, leveling a specific build for a professor is painfully slow and probably requires a lot of leeching exp, but once they reach very high levels, they have very high survivability in PVP situations, especially for a mage class, and they also have a vast array of overpowered support skills for large scale PVP.
The 'Super Novice' class, which is only accessible if you refrain from switching classes until level 40. Even if they're a Glass Cannon, they become extremely powerful in the endgame.
Runescape has the Ivandis Flail (And later Blisterwood Weapons), which is of the only weapon capable doing full damage to vampyres. It's basically a sickle on a chain attached to a stick, and starts out about about as powerful as farming implement on a stick would be. But, if you kill enough vampyres, take their corpses to a sacred site and cremate their bodies to release their souls, your skills with the flail magically improve and becomes an extremely powerful weapon (But only when used against vampyres). Blisterwood weapons, released in a later quest, are affected by this too. Only those start out powerful and become even more powerful.
The Sealed Sword, which is a 3-star sword that can be purchased following several battles against the Royal Jelly boss. While it is capable of causing random status effects, it only deals normal damage and has the same attack speed and damage as the Kamarin and Grintovec, sans their abilities to stun and freeze enemies respectively, and a far less useful charge attack than the two of them. If you can lug it around until it gets to level 5 (preferably with an extra weapon slot so you don't sacrifice carrying one of your actually useful special damage swords) it can be upgraded into the elemental-dealing Avenger and the shadow-dealing Faust, which can in turn respectively be upgraded into the Divine Avenger and Gran Faust, both of which are incredibly common among 5-star players for a reason.
In comparison its handgun counterpart the Antigua, which can be upgraded into the Silversix and Argent Peacemaker or the Blackhawk and Sentenza, is a bit more useful because it deals piercing damage and it can fire off six shots before reloading.
The Brandish is a 2-star sword that's basically a reskin of the Calibur with a unique charge attack. It can be upgraded into three elemental variations of it that can set fire to, freeze, or shock enemies, the Nightblade which is one of the only two shadow-dealing swords in the game (the other being the Faust), or the Cautery Sword, which is borderline useless due to Crippling Overspecialization; it's intended for destroying slimes, which shadow weapons already can do with ease.
World of Tanks: When first purchased, many tanks have weak engines and even weaker guns, forcing them to crawl across the battlefield to attack enemies they have little hope of damaging. Hanging in there and getting the experience required to unlock some upgrades, however, can make them into powerhouses. Perhaps the ultimate example was the Tier-5 KV Heavy, prior to the tech tree split in Patch 0.7.3. Incredibly slow and initially sporting a barely adequate 76mm gun, it could upgrade to some of the most powerful weapons available in its tier, including the 152mm "derpgun" which can one-shot many smaller tanks and a 107mm gun capable of penetrating heavy tanks two or three tiers up for significant damage.
One of the biggest offenders is the Tier-6 KV-1S Heavy. The stock configuration results in a slow tank with unreliable armor usually using an outdated howitzer, and it stays this way until the user grinds out every single upgrade. The top configuration that requires over 40-thousand experience? Medium-like mobility, armed with an extremely painful 122mm cannon, and one of the most whined about tanks in the game.
Also a benefactor of this trope is the Tier-4 JagdPanzer 38(t) "Hetzer" tank destroyer (prior to the introduction of the Waffentrager TD line in Patch 0.8.9). If to be accessed via the Tier-3 Marder II, absolutely nothing from the previous TD will be carried on to the Hetzer; while accessing it from the Tier-4 Pz 38(t) n.A light tank will only unlock the second out of the 4 compatible engines. Still, once fully upgraded and in the hands of a skilled player, the Hetzer becomes absolutely murderous on the battlefield, giving positive light to the infamous "Hetzers gonna Hetz" meme.
Digimon Masters Online: Oddly enough, one of the most popular Digimon in the entire Digimon franchise, Renamon, most definitely falls under this. It's even more prominent in that she gets the 'power' part of this trope upon digivolving to her final form. In this game, Renamon's skills are incredibly lackluster compared to the skills of many other Rookie Digimon. They have long startup with low damage, which doesn't do justice to her original incarnation as being one of the most powerful Rookie Digimon to exist (but, to be fair, her normal attacking capabilities are very good). Evolve it into Kyuubimon, and her second skill's damage also isn't worth its cooldown and mana consumption. Evolve it into Taomon, and you'll quickly get turned off by the enormous startup of her second skill, which deals a little less damage than the typical second skills of Ultimate Digimon. Evolve it into Sakuyamon, and she gets even more pathetic! She sports one of the the longest startup and one of the weakest first skills in the game. And then she has one of the weakest final skills of all the obtainable Mega Digimon, sporting the weakest final skill damage with an above-average length of cooldown. Endure all that however (or find an alternative way to level her up), and you're rewarded with Kuzuhamon. Treated as a Burst Mode in this game and thus given the stats of a Burst Mode instead of a Side Mega, Kuzuhamon is considered the strongest non-Jogress Data Type Digimon in the entire game, capable of dishing out her first and second skills alternatively. While her skills are just slightly better than the average Burst Mode skills in the game, what makes it appealing is the fact that her normal attack stats are hard hitting but slow, in which the 'slow' part could be completely eliminated by using a skill, in which she can quickly rinse and repeat a cycle of dealing lethal blows and throwing out a good skill. She deals an incredible amount of damage in that she can actually KO Digimon in the hardest levels of the Digimon Labyrinth before they get a chance to hit her back. You get all of this by leveling your Renamon all the way up to 65, and leveling starting from level 41 is a very slow and painful process for all Digimon.
The Terran Republic in PlanetSide 2 starts off with some of the worst weapons and vehicles - a carbine that cannot hit anything past 5 meters, a clumsy tank that loses every fight, anti-armor MAX grenade launchers that cannot kill anything, a weak LMG, etc. However, Terran players can unlock some of the most powerful weapons in the game - said carbine can be replaced by a gun with laser-like accuracy, their SABR-13 assault rifle can out-snipe snipers, those crappy MAX grenade launchers are replaced by dual rotary rocket launchers that can kill enemies from a mile away, etc. The biggest change comes in their Prowler tank, which becomes faster, more armored, and can unlock the Lockdown ability, anchoring it in place while increasing its fire rate, projectile speed, and reload speed by 50%, which when matched with an armor-piercing main weapon, allows it to kill anything within a mile - air, infantry, and especially vehicles. Infantry beware a locked down Prowler loaded with high-explosive rounds.
The Ecaflip from Western Animation/Wakfu are built on this. In the earlier levels, they are lackluster, mid-range close range fighters with a useless teleport, some very limited healing ability and chance-based attacks that do more harm than good. As they level up, however, they quickly turn into Glass Cannons who can heal if the party lacks an Enripsa, whose chance based skills become a lot more useful. For example, one of their special abilities, which in earlier levels could accidentally heal the enemy, does 1/2 the damage of the Ecaflip's previous attack with no cost when it is fully upgraded.
In Puzzle Quest: Challenge Of The Warlords, the Broken Shield you receive at the beginning of the game becomes obsolete almost immediately. But if you complete all of the Great Machine subquests, it is transformed into the powerful Shield of Albion, which can potentially make you immune to any spell using Yellow Mana.
In Puzzle Quest 2, the Templar's first offensive spell Shield Bash becomes stronger as the Templar's defense increases. Improving defense will eventually make Shield Bash the Templar's most efficient and powerful means of inflicting damage.
In Shift 2: Unleashed The Toyota Supra starts as a C-rank retro car. Then you can install the Lexus LFA engine and tune it up to an eye-watering 230mph(370kph) or outright insane 277mph(446kph) for you Speedhunters. It has decent handling to boot! Just watch out for the torque steer.
The FEISAR Prototype is this in Wipeout 2048. The vehicle is unique in that it starts off slow, but with each speed pad boost, the speed is permanently increased until it collides with a wall or completes a lap.
The British civilization in Age of Empires III is incredibly slow to start off with, but in the 4th and 5th ages their epic Musketeers and rocket artillery form some of the strongest armies in the game.
The Dutch and the Portuguese as well with a dash of Difficult but Awesome. The former has a slow start since their settlers cost Coin instead of food but can build banks to balance it out. Later on, they get excellent ranged cavalry with only 1 population instead of the usual 2, enough coin to afford expensive mercenaries, unlocking the best halberdiers the game has to offer, and one of the best naval city card bonuses including the powerful fluyt unit. The latter has the lack of settler card bonuses, thus leading a slow economic build up but if players can memorize the map using the Portuguese explorer's ability to use the spyglass, and get a Covered Wagon with every advanced age. Meaning, experience Portuguese players in the late game can spread their base around for resources while having the best naval bonuses, excellent dragoons and light infantry, and their musketeers that rival the British.
An Imperial Guard Squad at the beginning of the game can't shoot, can't fight, dies like flies, and runs screaming in terror at the slightest problem. By the time you reach tier two, the 5 man squad is now 13 men, 5 of them have heavy weapons, and with a commissar, the IG Squad is unbreakable and can fire twice as quickly as normal. In this state it is the most powerful non-unique infantry unit in the game. Watch the Space Marine terminators die before they reach range...
The Ork army is this. At first you only have Slugga and Shoota boyz, with minimal squad numbers and abilities that suck outside their namesake and are crap without backup. Fully upgrade them and outfit them, though, and a full squad of slugga-boyz can rip through any other unit in the game.
While all commanders are no slouch during the campaigns, the Chaos Lord stands out in that he starts out squishy like the Space marine commander, but after obtaining his last upgrade (daemonic ascension) he permanently becomes a Daemon Prince, who is powerful enough to go toe-to-toe with any of the relic units in the game. Because he's your commander though, you get him as soon as the mission starts.
For about the first half of the Dawn of War II campaign, Cyrus deals pathetic damage, dies easily and is the epitome of Useless Useful Stealth. Level him up, give him a sniper rifle and various explosives, and allocate the right traits to him (especially the ones that make his stealth incredibly useful) however and he becomes the single most versatile character, effective against all enemy types, and with careful player oversight is capable of soloing missions.
A piece of equipment, the Heavy Bolter for both Space Marines and their Chaos counterparts. It trades off damage capacity for rate of fire and suppression. Squads carrying heavy bolters can be devastating, but equipping a single hero with it is underwhelming, as many times "kill it dead" outweighs "make it not be able to run at us as fast" as a strategy, especially since (typically) two of your other heroes are melee oriented. But the semi-random wargear drops (and one named drop) have a single effect that trumps all others: "Cause X% damage in an area." This coming from a gun with likely the highest rate of fire in the game, equipped to a character who has hopefully taken the skill that lets them ignore the "set up" timer before and after moving, and each shot fired causes a small explosion; suddenly those massive hordes swarming your lines are not so massive.
In the PC strategy game Dungeon Keeper (1997) by Bullfrog Productions, you must build training rooms to train up your monsters; and a few monsters will become far more powerful at maximum level. Demon Spawn, while moderately good fighters at low level, become Dragons at level 10. Thieves can be trained into Knights, identical to the Lords of the Land you've been fighting. Even the lowly Imps get this. As workers, their fighting ability is pathetic, so most players won't bother. But at level 3, they get Haste, letting them mine through stone like a buzzsaw, and at level 10, they get the ability to Teleport.
Germany starts out divided into loads of weak one province states that are effectively irrelevant compared to other monster countries like France, Spain, or Great Britain. However, with some skill (or just a constant series of wars) a player who conquers enough German states can create Germany who's sheer size and population can make it one of (if not THE) most powerful countries to play in the game, especially in Victoria: An Empire Under the Sun where a united German state gains so many advantages it basically becomes a Game Breaker. That's right, a entire nation is a game breaker in this game.
Kingdoms in India qualify. They start out with a far steeper technology curve than European powers, their religions (Sunni Islam and Hinduism) are statistically inferior to the Christian religions, and even the strongest powers are at best mid-weight by 1399 European standards (and they fall back further as time goes by). But! If an Indian prince grows strong enough, it can declare the Kingdom of Hindustan, which controls an area nearly as large as Ming China, without Ming's governmental flaws. And as for the technology issue, that can be solved by westernization, which will rapidly lead Hindustan to exceed Europe in tech level.
Japan. Anyone who knows anything about Japanese history will know that those backwards island fools with the fancy swords might not look like much, but wait and see when they drop the traditions and start getting things like guns, railroads and factories. Indeed, Japan starts out as a small, uncivilised country in East Asia, but it gets a huge bonus to westernization and industrialisation. This combined with a disproportionately large and relatively well-educated population means that Japan stands a very good chance of becoming a modern, secondary world power, capable of dominating China, Southeast Asia and the Pacific rim. In fact, in the hands of a half-decent player, Japan can easily reach GP status.
China, for all it's notorious status as a nigh-unplayableButt Monkey, is an absolute monster once it finally gets it's shit together and gets past a plethora of hideous issues including widespread government incompetence and corruption, a hilariously backwards stance on scientific development and public education, constant rebellions and a terribly inadequate military that relies mostly on overwhelming numerical superiority. The AI will never manage it, but some good players can and have done.
Dr. Neurocide in Evil Genius, who can be recruited very early in the game, is worthless in a straight fight and thus very difficult to level. On the other hand, both of her unlockable special abilities are spectacularly useful in certain situations; she can blast an area with a hallucinogenic gas that masks anything affected and keeps agents from noticing it, meaning they can walk through the middle of your morgue and not pick up on it, and she can also deploy a nasty knockout gas that'll plant pretty much anyone, Super Agents included, flat on their butts if they get stuck in it long enough.
Majesty has an extremely annoying character type. The wizard. When first hiring the wizard, he will be extremely weak, going up against the weakest sewer rat is a death wish for a level 1 wizard. However, nurturing them to higher levels will make them unstoppable killing machines.
Rise of Nations gives you the Lookout or Observation Post, a largely useless structure whose only purpose is to provide large LOS. It can't be moved, it has no attack, and you could just as easily use a couple strategically placed Explorer units or patrolling Cavalry. But once you reach the Industrial Age, it turns into the Air Defence Gun, which can destroy biplanes in four or so hits while costing little more than the Lookout. In the Modern Age it turns into the even-more-powerful Radar Air Defence, which has massive range in addition to being a superpowered airplane-killer, so you can make nine or ten and set up an impenetrable flak curtain that will effectively deny your enemies any form of air support. But its greatest evolution has to be in the Information Age, when it turns into the SAM installation. These consist of three homing missiles arranged on a little tripod thing, which will be ripple-fired at the first sign of an enemy plane, and which then will be reloaded in seconds. Build multiple ones for a bomber-killing, fighter-vaporizing Macross Missile Massacre. And all of these auto-target.
The Kol Battleship of Sins of a Solar Empire, despite its glowing description in lore, has poor antimatter reserves, unflattering damage and can be beaten by most other capital ships in a duel. However, with enough levels, its antimatter reserves grow to the point where it can use its abilities much more freely and the Finest Hour Limit Break can dramatically turn a bad situation around. Then it becomes the beast the story claims it to be.
The UNSC in Sins Of The Prophets initially have to outnumber the Covenant many times in order to win. By late game, the gap closes, such that the Orion Battlecruiser or Thermopylae Supercarrier only needs two-to-one odds to beat a Covenant capital ship.
Portugal. Early game, laughable militia and light infantry. Late game, tied with Spain as the best overall army list.
Scotland. One fairly impoverished town province with Highlanders (admittedly fairly good light infantry), Peasant/Highland Archers (terrible archers), no crossbow or gunpowder units at all, and only the bog-standrad knights along with Border Horse (fast but poorly armed and armoured light cavalry). The Scotland faction usually just gets steam-rolled by England in the first few stages of the game. However, if you hang in there, you end up getting Highland Nobles, Noble Swordsman and Noble Pikemen (respectively: very good and cheap heavy infantry, Dismounted Chivalric Knights but cheaper and on steroids, and the second-best pikemen in the whole game), access to Knights Templar and Hospitaller guilds, access to gunpowder and crossbow mercenaries, and the cheap and fairly-decent Noble Highland Archers unit.
Russia in Empire: Total War. Yes, 9 provinces sounds good, but most of them can't pay for their own upkeep, and you mostly just have crappy militia that can only win through Zerg Rush tactics. Get hold of a sea port, build up some infrastructure, encourage growth in your poor provinces, and research some technologies, and Russia becomes a very different beast.
The Otomo clan from Total War: Shogun 2 are Christians, which means everyone in Japan hates their guts. Their initial leader is dishonourable, adding to the public order penalties from Christian/Buddhist conflicts. They start with a matchlock unit, but it isn't very good and costs a ton of upkeep. They share an island with the extremely aggressive and expansionist Shimazu. They start at war with two factions, who also happen to be allied to each other. However, if you overcome all these downsides, you'll find yourself swimming in money (thanks to foreign trade ports), armies bristling with matchlocks (which are short-range, but MUCH more powerful than bows) and nigh-unstoppable fleets (thanks to European-style ships armed with cannon).
The Ikko-Ikki, thanks to their Jodo Shinshu Buddhist faith and rejection of the feudal system, are also The Scrappy of feudal Japan, and as such don't have any samurai units besides the somewhat limited katana/bow/yari ronin. They do, however, have very powerful warrior monks, including matchlock monks, as well as the ability to take over provinces via rebellion! Their main problem is, however, the simple fact that monks take quite a while to acquire, moreso if you want to upgrade your blacksmiths and fletchers beforehand.
The Night Elf Archer in Warcraft III is the weakest of all basic units. However, once you reach the late game you can improve range and damage, make it ride a hippogryph, a flying anti-air unit greatly increasing HP and mobility and unaffected by melee attacks. And since they can dismount, attacking aerial units find themselves suddenly facing twice the targets dealing more than twice the damage.
The Siege Engine starts off as a Joke Character that only works on buildings, but upgrade Plate Armor and Ranged Weapon damage (when ranged units generally use leather armor), add in its rocket upgrade and watch the enemy's entire air force disintegrate under a hail of missiles, while their weapons just bounce off its armor and then plough them straight into their base and destroy it.
Starcraft has the Zerg. Due to their peculiar method of creating units, they are extremely vulnerable to early attacks, but if left alone long enough, they will bring forth armies of Ultralisks (highest HP of all ground units) and Guardians (a flyer that outranges every defensive structure and ground unit). In Starcraft II, replace Guardian with Brood Lord (in addition to huge range, every attack will now Spawn Broodlings).
The humble Zergling. Made two-for-the-price-of-one (at 50 minerals, it's the same as every Worker Unit and the Marine) and pretty much exists only to be spawned and die in large numbers. However, by end game it gets upgrades that increases its already impressive movement and attack speed, letting it shred apart armies... when spawned in large numbers.
The sequel takes it even further, by giving all Zerg units speed bonuses when on creep. It also gives them an invisible creep spreader that lets their armies move lightning-fast across vast distances. Oh, and they can now morph into Action Bombs.
And even further in Heart of the Swarm's campaign (once you've progressed far enough), where Zerglings can now jump cliffs/spawn instantly and three at a time, while Banelings either split into smaller Banelings or gain the ability to jump into enemies over their aliies' heads.
The "Est archetype": a character that joins the party late and it looks like Can't Catch Up is in full effect, since he or she is quite fragile, but if the player is patient and levels him/her up adequately, after promotion the character will become extremely powerful.
One non-Est example is Leaf, who joins in the 2nd chapter of the 2nd half (that starts with a new group of characters) and starts out as a mere swordfighter, but can eventually use almost every weapon in the game.
Raquesis, who joins during the first half and is just as weak (though she has the benefit of being able to use healing staves along with swords), but promotes into the insanely powerful Master Knight (a class she shares only with Leaf).
Also, Corple if you paired Sylvia with Levin, Azel or Claude! He joins you two chapters before the final battle as a level 1 priest but if you decide to put the effort into training him up (aka do a lot of pointless healing with a Recover Staff) he'll be one of your best spellcasters. (And if he's Claude's son a great frontline healer when you're facing a lot of Sleep or Silence Staves.)
Finn in Genealogy of the Holy War (much less so in Thracia 776) zigzags between this and Crutch Character. In the First Generation, he starts off quite weak and is disadvantaged by the fact that he uses lances when the first chapters are full of axe-users, but because of his good growths, the Prayer skill and the Hero Lance Cuan gives him in chapter 2, he becomes a valuable asset to your army until he leaves (at the end of chapter 3). Then, in the Second Generation, he is normally much stronger than the characters he's protecting (Leaf and Nanna) at the beginning of chapter 7, but because most of your army can be made of Game Breakers, he ends up being outclassed in the last chapters.
Homer from Thracia 776 is a prime example of a Magikarp Power. He joined underlevelled in a rather difficult and pretty late chapter, followed by a chapter with Fog of War. He specializes in Light Magic, which is rare, and he can't even use the Resire tome that you acquired at the same time he joined the team, and he can't use Wind Magic. Then you realize that he has the Elite skill to double his exp gains, he has stats growth that is even better than Asvel, PCC of 5 which means on the second attack, he has massive chance for a critical hit. He also promotes into a Sage, which allowed him to use staves(a huge plus since the Staves are poorly ballanced in Thracia, although Homer is not expected to have a high staff rank in endgame), an extra rank in the elemental magic and 2 rank in light which allowed him to use better tomes including Resire and the Wind spells. It helps that Sage have a promotion bonus that looks like something out of Genealogy of the Holy War which was REALLY massive when compared to the current standards and Thracia's standards alike.
By extension, a lot of unit who can promote into a Sage count in Thracia, this includes Asvel, Linoan and Sara:
Asvel started in better position as he joined earlier as a Squishy Wizard with an extremely powerful personal weapon which helped him during the early stages and turns him into an amazing boss killer. The promotion into Sage increased his durability a lot, and with only 7 levels with the help of the Sety Scroll, he is guaranteed to have a maximum speed, and a good chance to have an acceptable magic and skill, both of which are boosted in high amounts by the promotion bonus. As far as offensive magic goes, the only character who can outdo Asvel is the Glass Cannon Olwen, and the Eleventh Hour Superpower Ced.
Linoan and Sara joins in a late chapter rather underlevelled with no personal weapon, and Linoan is forced to promote with a late game events. However, Linoan can use the Resire tome from the start and is likely the only person who can use it, and she can perform staves duty, helped by her solid stats growth. Sara later gained a personal weapon that is rather useless other than giving the acess to That One Sidequest, however she has better starting staves rank than Linoan, a massive stats growth, can promote earlier than Linoan, and her skillset are filled with three of the best skill in the game, which includes Elite. And they happen to exist in a game where having a good staff rank right from the start is an equivalent of winning a grand prize in a Superpower Lottery.
Lyn and Eliwood possess Magikarp Power. They are pretty fragile units initially, and require special effort to level them up. However, their upgraded forms are rather strong. Eliwood actually gets his class up through a story event, but how strong that is ultimately depends on how much you were willing to use him before his class up, so it fits.
Nino, who joins at level 5 about 5 chapters away from the end of the game. She also has some of the best growths in the game, and can be made very powerful if you're willing to slow yourself down. Less extreme, but also applies to the likes of Bartre, Rath, and Heath.
Astrid in Path of Radiance is a definite example. She starts out so weak that she cannot take a hit from anything. She gets experience much faster than everyone thanks to a personal skill though, and if trained she rather quickly catches up and then passes the other characters in levels. Not only does she get great stats, but her promoted class, Paladin, is extremely broken.
Sanaki from Radiant Dawn veers into this and Glass Cannon territory. She joins very late in the game and has a few powerful weapons, but is marred because a) you've had three parts to train your other characters, b) Her strength is so low she takes a penalty from using her own special weapon and c) Has very low health, making her the Glass Cannon. Despite this, she has the best growths in the game.
Laura from the same game also counts, but she takes the trope WAY too far. She's a White Magician Girl with insane growths in both MAG (third-best in the game, behind Micaiah and Soren) and SPD (tied for best with Elincia), but not only can she not use offensive magic until she promotes, she starts at level 1. Staves also give painfully low EXP.
Vika is this. She has one of the worst availabilities in the game (if not the entire saga, being a new character introduced to Radiant Dawn) yet she has pretty high growths for a Laguz. It takes a lot of babying, but she pays off. Her main problem is also that she joins very late, and in the rest of part 4, you have the Laguz Royals, so there's really no point in using her when you can take Naesala if you want a raven with you in the final battle.
Gordin, in the Fire Emblem remake Shadow Dragon starts off as a fairly bad archer. His only notable strength is his above-average defense. If you have the patience to get him to around level 15, and then promote him...his promotion gains are VERY good, helping to overcome his early game issues.
His brother Ryan in New Mystery is pretty much the same, but better growths and less early-game issues. In fact, Archanea's Archer class itself is often considered this: it has bad base stats and movement equal to the game's Mighty Glacier class even though Archers are supposed to be Fragile Speedsters, and promotion to Sniper gets rid of both these flaws.
There's also Radd. You get him pretty early but his base stats are so bad that he is worse than regular enemies in the same level you get him. But if you level him up, he will become a Lightning Bruiser with unusually high defense for a myrmidon.
Wolf and Sedgar. Despite the fact that they join prepromoted and give signs of Crutch Character, if you look at their stats, you might be surprised because of how low their bases are. They actually have the best growth rates in the game.note especially in health, their growths exceed 100% meaning they're guaranteed at least 1 HP per level up and have a chance to get an additional point.
Sheema from Mystery joins at level 1 promoted into General. However, not only her stats are very decent for a prepromote, she's also possessing great growth rate that if you take your time to level her up in the short time she's in, you'll be able to make her tank damages easily or become a Lightning Bruiser on a certain forthcoming That One Level (if you haven't been training an Armor Knight/General).
Fire Emblem: The Sacred Stones: A more straightforward Est is L'Arachel, the only Troubador in the game. When she's recruited, she's simply a mounted White Magician Girl, which is handy for mobile healing but no good for combat and therefore both vulnerable and agonizingly slow to level up. With the patience to finally get L'Arachel to level 20 and promote her into a mage knight or valkyrie, however, she has been known to clear the first floor of the Bonus Level Of Hellby herself, often gaining her remaining twenty levels and capping several of her stats in a single mission!
Fire Emblem Awakening: Donnel (aka "Donny") seems designed with this trope in mind. He joins with pathetically low stats and in the weak Villager class that can't even promote. His class, however, does give him access to a special skill that boosts all his growths by 20% with no penalty. Even his Character Development reflects this trope; initially he sees himself as weak and useless and the whole point of his sidequest is to convince him otherwise by letting him get a Level-Up. Unfortunately, he still manages to be a Tier-Induced Scrappy due to factors besides his statsnote Mainly the fact that the Villager class exclusively uses Lances, but none of the classes he can 'graduate' to can (they're the Mercenary and Fighter lines), meaning he has to spend ages building up a Lance rank for nothing., but luckily the 'Aptitude' skill can be inherited by his kids (who don't have his bad start), turning them into utter Game Breakers.
In Age of Wonders you can buy dragon hatchlings. They start off rather weak and are often targeted by the enemy, but if you can build their experience to gold medal rank they will grow into full size dragons.
A hidden example in Galactic Civilizations where, if you have your race take the morally good path you find out about Telepathy - that almost all telepaths born with severe physical disabilities, they don't survive in the evil races, but if they do... What this means is that, as you're a good race and look after your people, then you get access to a series of telepathic defensive technologies which are far more powerful than anything else at that tech level.
To get a wizard to learn the Arcane Omniscience skill in Heroes of Might and Magic V, you need to let them learn a specific set of skills note Sorcery, Enlightenment, and War Machines, which means neglecting their other skills and being forced to rely on their army and low level, low power spells for most of the early-to-mid game. Once they learn Arcane Omniscience, however, they instantly have every spell in the game added to their spellbook, and can cast them all at expert level mastery.
the Morrigi, who are also Difficult but Awesome. Their destroyer-class ships are fragile and strategically sluggish. Their population growth, terraforming ability, research speed and industrial growth are awful. However, if you know how to play them and get them to lategame, you find they have good to great chances at the best techs in the game, and their dreadnoughts are monsters.
Liir did it first; they suck at start, being Glass Cannon without the cannon due to their few weapon mounts with poor firing arcs. However, they have faster research speed than the rest and similarly good to even better chances at the best techs than Morrigi. A Liir player who can avoid getting crushed in early game will out-tech the opposition with frightening speed.
In the sequel the Zuul are turned into this, with a weakened early game but the lategame goal of summoning the very powerful Suul'ka to aid them.
Yggdra Yuril Artwaltz from Yggdra Union begins the game as a relatively useless character with stats well below every other character in the game (excluding the summonable extras). However, halfway into the game, she will gain an upgrade that not only turns her into a character on par with some of the strongest characters in the game, but also gives the Always Ace ability, the equivalent of arming her with the ability to abuse nearly every card in the game. That, added with the final equip Fanelia can turn her into a Game Breaker that can literally OHKO every single unit in the bonus stage by herself.
Sniper class in XCOM: Enemy Unknown. Unlike other classes at "Squaddie" rank, Snipers remain nearly as useless as rookies. The sniper rifle is more accurate as range increases, but Squaddie snipers have only their own limited sight radius to work with, making them poor shots. Add to this that the sniper can't shoot or overwatch with their primary weapon once they've moved, and you've got the movement of a Mighty Glacier with the power of a Fragile Speedster. Once they gain their second rank up to Corporal however, they (potentially) gain "Squadsight" a true Game Breaker that lets the sniper fire at any enemy the squad can see, so long as the sniper's view to that enemy is unobstructed. A Colonel-level sniper with "Squadsight" and "In The Zone" perks can wipe an entire map clean of enemies in a single turn, given the right circumstances.
Good old "useless" Colin from Advance Wars. He's the rookie who's units have reduced attack power in exchange for a meager 20% discount on manufacturing units, and his first major mission is a Hold The Line Style setup which goes out of it's way to remind you he is useless. Of course, later in the game when the strong units (Like Battleships and Bombers) are in use, his weakness is suddenly a moot point since his units are still doing tons of damage and that discount means you're saving thousands of bucks on new units. Happy smashing!
The sequel allows you to team him up with Kanbei, his polar opposite who has insanely strong units that are much more expensive to produce. This is one of the strongest teams in the game and the two don't even get a tag bonus.
The first weapon obtained in BioShock is a wrench, the only melee weapon in the game, which does so little damage, even with the 4x multiplier of Electrobolt, it is at first only good as an Emergency Weapon. Then the player obtains the tonics that boost its attack speed and damage, as well as its damage against unaware opponents (which includes enemies stunned with Electrobolt or attacked by Insect Swarm), all of which stack with each other and the damage bonuses provided by the Research Camera and suddenly every single enemy in the game aside from Big Daddies and the final boss is dying in a handful of hits.
In Bioshock Infinite, there's the Pistol and Machine Gun. The Pistol starts off as a fairly weak weapon which is good against minor enemies but not against other ones. Most gamers ditch it for other weapons. But if you stick with it and upgrade it fully, or have the correct gear, it becomes a weapon that provides fast fire, solid performance at all ranges, carries up to 31 rounds when you get to Soldier's Field and is an excellent sidearm overall. The Machine Gun is effective early on, but it isn't as good against tougher enemies. Fully upgrade it, and use the Bullet Boon or Ammo Advantage gear, and the Machine Gun will suddenly have a massive clip size, carrying even more bullets than the Crank Gun, is as effective as the Shotgun from close to medium range, can take out enemies with in a few shots, and will almost never run out of ammo because it's the most common weapon in the game.
Krieg the Psycho from Borderlands 2 is extremely underpowered at low levels. His skill choices are either extremely narrow in application at low levels or just not useful enough to carry him through like the basic skills of the other characters...or it might just kill him outright by delaying his shield recharging or setting himself on fire. Level him up high enough, though, and he can become a damage-dealing monster, able to slaughter entire hordes of enemies while healing himself or chaining enough damage to annihilate raid bosses in an ever-increasing rain of blood-explosions.
Jedi Outcast: Force Lightning and Force Grip start off very weak when you first get them, with Lightning barely doing any damage to enemies, and Grip only being able to stun enemies for a few seconds. At their highest level, you can clear out entire rooms with Lightning, and use Grip to fling enemies off of ledges and disarm them, which is useful for quickly ending lightsaber duels.
Jedi Academy: Force Rage. It makes you stronger while eating your health and making you more vulnerable to damage for a few seconds after it ends. At level 1, health drain is HUGE and your strength increase is... not. It doesn't last very long, and the time spent doing the activation pose does count, and you can take damage during it. When it ends, and all or most of the enemies you were trying to use it against are all still there, you. Will. Die. So why invest in it? Because Force Rage 3 is another story. You'll hand out epic beatdowns and hardly notice the drawbacks.
Your starting weapon, the plasma cutter. Upgrading it improves it so much that it's entirely feasible (if not quite as fun) to use no other weapon for the duration of the game. There's even an achievement for doing this.
The Pulse Rifle chews up ammunition FAST, does barely any damage, and has a ridiculously small hit area. If you upgrade it though, it can become an incredibly accurate and ammo economic limb remover from over a 100 meters.
The Grinder in Red Faction: Guerilla is somewhat like this; when you first get it it's Awesome, but Impractical with a slow fire rate and shots that sometimes aren't an instant kill (on hard at least), after getting the explosive upgrade (which between the higher damage, splash damage and building and vehicle damaging capabilities makes it FAR more versatile) and the fast shot upgrade (which fixes the weapons biggest flaw) it becomes a good all-round combat weapon.
The Handcannon, which can't even be purchased until you've beaten the game at least once, and whose ammo is incredibly rare, making it pretty much a paperweight once you own it. Spending a ridiculous amount of money to upgrade it, however, gives it infinite ammo and a firepower rating that lets you one-hit-kill pretty much everything in the game.
The 9mm handgun you begin the game with is arguably the weakest firearm in the game. However, once you max it out it becomes five times more likely to get a critical headshot which, so long as you hit enemies in the head, virtually turns into a one-hit-killing machine (bosses/mini-bosses excepted of course).
In principle, all spells work a little bit like this, because they only start to function properly as advertised after some practice (ie. dozens of castings). However, it's really exemplified by some of the most powerful spells, such as Demon Exodus (destroys all demons in a battle) and Goddess' Wrath (destroys all enemies). Yes, they'll do that eventually, but it takes a while before they do anything at all to speak of.
Melthas, who is almost completely useless. His only offensive spell is Small Fireball — the weakest offensive spell in the game. His healing spell isn't much better either. All of his other abilities are support spells which will almost never be used when you can just freeze the entire battlefield with Sira (who will ALWAYS be in your party if Melthas is). That changes when he gets Demon Exodus, and upgrades it to at least 50% of its full power, at which point it will instantly eliminate all demon type enemies (which include both the most powerful and the most irritating non-human enemies in the game) on the field.
Harriet's Wrath of the Goddess. When you first learn it, it will use up all of her energy (and quite a bit of her health if said energy is not on 100%), and disintegrates a single enemy at most. Develop it to 100% and it's an instant I Win button, as it will destroy everything except Ned's type 2 androids. Of whom you will only have to fight one.
Dual-classing in general. You abandon your old class and start taking levels in a new one, which suppresses all of your old skills until your new class becomes a higher level than your old one (so if you, say, dual-class from thief to mage at level 7, you need to hit level 8 as a mage before you get your thief skills back). Dual-classed characters usually have to spend a lot of time playing 'catch-up' to the rest of the party and gain no HP until their new class bypasses their old one, and it is crippling if a vital party member (like a thief) does it while you have no spare, but the end result is a whatever you dual-classed into with the HP and skills of the first class stacked on top of its own. Applies less in the second game, where it's easy to just take some of the benefits of dual-classing without the cost; several potential party members are already dual-classed, and the Player Character could just switch right at the start of the game and catch up quickly, as the first dungeon gives a lot of experience (from spell scrolls).
The sequel gave us the Sorcerer class. Initially it seems far weaker than a normal mage. Instead of learning spells from scrolls, it can only learn a total of 5 spells per level, which are slowly chosen over the course of level-ups. In other words, make any bad picks and you're screwed. Even the official strategy guide for Throne of Bhaal recommends against choosing a Sorcerer. However, the Sorcerer is able to cast an unprecedented 6 spells per day of every spell level (an amount only outdone by Edwin) and can pick which spell to cast on the fly, flexibility only matched by a Reckless Dweomering Wild Mage (but without the wild surge). In Throne of Bhaal, where the mage HLAs all count as learned spells, the Sorcerer dominates the mage.
The Monk (also in the sequel) starts the game almost crippled by high armor class (high being bad) and the fact his fists don't count as magical weapons. By the time he hits high levels, not only are these problems long cured, he also gains insane magical resistance and fists that can outdamage Dual Katanas.
With the Ascension mod installed, that +2 Sword of Chaos that you've been carrying from the first dungeon in Shadows of Amn will become a +4 weapon with better special abilities if you give it back to its original owner Sarevok.
An archer rogue, more so than any other class, fits this role, especially if you want to invest talents into lockpicking. While melee classes such as Warriors and Dual Wielding Rogues get access to decent weapons sooner and mages start out strong and just get stronger, an archer is...somewhat underwhelming in the early-game thanks to a lack of decent bows and relatively weak initial talents. However, archers have extremely powerful late-game talents such as Scattershot, which does better than normal damage to and stuns just about every enemy you're facing at once and is almost impossible to resist, and Arrow of Slaying, which can deal up to several hundred points of damage with one hit (up to 10 times normal damage in the right circumstances), and is perhaps the best way to deal with enemy casters before they get in range to do real damage. Several of the unique bows that are found later in the game are also very powerful. By the endgame, a properly built Archer Warden will be the best damage dealer in your party.
The Bard specialization starts out rather spoony, as the base stat buff and initial skills compare very poorly to all other specializations. But the effects scale up with Cunning, which a smart Rogue develops to increase their lethality. Since the song effects the entire group, the value is multiplied by each conscious teammate. In the end, there is no specialization across all the classes is as powerful.
If you get party member Liara early enough, she's pretty weak. She can't be trained with any weapons and she can only equip light armor. However, if you get the party, and by extension her, up to level 60, and distribute her skill points appropriately, she will be the most powerful biotic party member with extremely fast recharge times on all of her skills.
Tali starts as just an engineer, however her Quarian Machinist Skill and another of Skill both improve her shields. If you max both, and give her proper Armor add-ons to further improve her shield and shield regeneration, she can be more durable than a Soldier/Infiltrator and second only to Wrex in sheer survivability (with the exception of Immunity). She'll have more shield than most heavy armor users.
Kaidan starts with only a weak throw and sabotage, but with levels and by maxing out his class skill, no other party member can compete with him in the sheer variety of ways he can screw with enemies, with recharge times on par with Liara. Of course, he's still just aSpoony Bardby comparison.
In Mass Effect 2, DLC party member Kasumi is extraordinarily weak, even more so than Jack. However, careful distribution of her skill points will turn her into a Glass Cannon with abilities that can disorient enemies, overload their shields, and severely weaken most mooks (or one-shot them in the easier difficulties, where it becomes Awesome, but Impractical by virtue of sheer cooldown time.
At the start of the Dark Brotherhood questline you're given a crappy little dagger that is basically useless compared to everything else you have. At the end of the brotherhood quests, the dagger gets enchanted and becomes a fairly powerful enchanted weapon that, if nothing else, will get you a decent amount of money if you sell it.
There is also the Chameleon spell, which would make it possible to sneak well, but even with 97% Chameleon, you would be found by enemies after the first strike on them, seeing as they are all somewhat Psychic (which made it a waste of magic against multiple enemies). However, if you managed to get 100% Chameleon (which could be done permanently), you would essentially never die, as only scripted characters or monsters could find you. Add max sneak, and you could have 6x damage on every attack in addition to the invisibility. To get this with a spell, armor would often lower the percentage and ruin it, forcing you to become an Invisible Streaker (if underwear had not been grafted on to your body).
Thief skills. These abilities initially are nothing impressive: with pickpocketing you can occasionally find good loot in someone's pockets, sneaking lets you avoid getting in fights, speech nets you slightly higher prices, and lock picking makes opening locks a little easier. Invest in their perks, and once you've built up your experience with them, you can sneak during combat with an enemy, allowing you to steal his armor and weapons while he's trying to find you again, then drop a few bottles of poison in his pocket, causing him to die instantly, or you can use a dagger to slit his throat, which, due to sneaking's perks, will do as much damage as a daedric warhammer to the face would (x15 sneak attack critical damage with a daedric dagger is insanely powerful, and with an easily found enchanted item found in the dark brotherhood questline, you can easily make it x30). Then you can search whatever treasure chest he was guarding and get much better loot due to lockpicking's perks, which you can sell for drastically higher prices at the store.
Archery. Initially, the damage isn't impressive, but an ebony bow and arrows will, from a base, unperked sneak attack, drop many foes in a single shot (Draugar deathlords with Ebony bows can drop even a heavy armor wearing character in a couple of shots). Sneak allows you to change the damage bonus for sneak attacks with bows from x2 to x3. This is enough to kill just about anything short of a dragon or high level dungeon boss with a single shot once you're using Ebony or higher.
Alteration magic, to some extent. Yes, the various armor buffs can be useful, but a Destruction-minded mage may prefer to Stun Lock her enemies so they never reach melee range, while a Conjuration specialist may let his summoned minions do the fighting while he hides in the next room. But once your Alteration skill approaches level 75 you can buy the Paralyze spell, which will render the majority of enemies helpless for ten seconds or more. Start a Wall of Fire underneath that Draugr Deathlord and watch him burn, and if he starts to get up, just zap him with Paralyze again.
"Euclid's C-Finder", a thing that looks like a toy raygun and is indeed being used as such by a pair of kids in Freeside. Initially, you never find ammo for it. But once you power up ARCHIMEDES II, the little gun becomes the targeting laser for it.
The humble Varmint Rifle is the first weapon you get in the tutorial. You get it in poor condition, it suffers from low rate of fire and low clip size and its one good point, high accuracy, is largely useless with just the iron sights. But once it's fully repaired and upgraded, it turns into an extremely light-weight silenced sniper weapon that can take out even late-game enemies with a sneak attack headshot. On top of that, it's cheap to repair and maintain, ammo is plentiful and it can be loaded with AP ammo that'll go through most non-powered armor types without even slowing down in return for a barely noticable 5% reduction in damage.
The Laser Rifle may possibly qualify, while it has low spread, can be found quite early( you can find two in Nipton in a rather poor state, and if you're really lucky, one of the diggable graves at the Yangtze Memorial.), and a respectable zoom, the rather low damage and the fact it uses Microfusion Cells doesn't quite allow it to be an amazing weapon out the gate early on, but if you are lucky and/or patient the town of Novac has a merchant that sells all three modifications for it, a scope that puts the zoom on par with that of the Gauss Rifle, Focus Optics, that give it +3 to damage, and finally a beam splitter that turns the one beam into three that can hit the same spot all at once, turning it into a weapon capable of carrying you through all of the game, save the Dead Money Add-On.
In Freedom Force, Man-Bot is slow and clunky with a weak blast attack, although he has a powerful punch if he can connect. However, if you can bear with him, he eventually gains the ability to fly, and more importantly can be vital to the team by using his tremendous Energy X generation to transfer energy to his team mates, allowing them to use their own abilities much more frequently.
If the player gives their custom IMP merc 85 (the max) wisdom (that affects how quick they improve) a merc that was "meh" everything, with a little practice, becomes perfect at everything.
Same goes for some of the other mercs that you can hire, notably Ira, who is assigned to you at the very start in Jagged Alliance 2. She seems like a mediocre medic and awful everything else... except for her 83 wisdom that allows her to quickly become one of your elite soldiers.
Gumpy. An overweight, unattractive dork who throws dated pop-culture references around with a speech impediment. He's okay-ish with explosives and terrible at everything else. However, his wisdom is 93. He can potentially take several levels in badass.
The Monk character class. Most players avoid it because it doesn't exactly sound exciting - he can't wear any armour, and can barely use weapons. As expected, his initial attacks pale in comparison to those of sword-wielding warriors; however, level a monk enough and he becomes one of the strongest attackers in the game, hitting harder than most magic swords several times per round, and having ridiculous spell resistance above almost all items in the game, with great saves for anything that gets through.
In the expansion packs, there are Shifters. Their physical stats don't matter when they're shapeshifted, so you're pretty much encouraged to Min Max and up their Wisdom scores. The problem, unfortunately, is that they need to take 5 levels of the mostly-useless Druid to get them, and their forms are quick-moving but painfully frail until they reach level 7, for a combined level of 12 to turn a physically weak, magically inept character into an Awesome, but Impractical Fighter-wannabe in a game that you're expected to beat around level 15. In multiplayer and the expansions, though, you can get characters up to level 40, and past the "epic" level of 20 you can start learning to boost a character's base stats. If you got them a base wisdom of 16 or higher, and you invested every point gained from levelling up into wisdom, and for every point below a base 20 wisdom you used an epic feat to boost wisdom, then at the level cap you could get the ultimate feat for the class: turning into a dragon.
The Bard class. While they manage to avoid being a Spoony Bard at the beginning, they're not particularly amazing. As they level up, though, they gain stronger and stronger songs like Curse Song (which affects multiple enemies at once), Legionnare's March (which affects your entire party), and Hymn of Requiem (which damages multiple enemies while healing your entire party). While they aren't Game Breaker status, a properlly-levelled Bard can be the best support character in the game.
In Planescape: Torment, one of the spells you receive for unlocking and interpreting the Unbroken Circle of Zerthimon is "Missile of Patience," which fires a single bolt of energy that does a negligible amount of damage. Until your mage reaches level 11, that is. Then it summons a giant repeating ballista that fires many bolts of (more powerful) energy at as many targets as you can hit before the spell ends.
The Paladin class. Leveling up a Paladin was absurdly boring. A Retribution Paladin (the damage spec) didn't even get a damage strike until level 40, meaning that they basically threw up a seal and auto-attacked for 40 levels, tossing in a Judgement every 10 seconds. But at level 80 (in Wrath, Retribution was basically non-existent till then), they were one of the strongest dps specs in the game, if not the strongest. They got toned down a bit, but thankfully in Cataclysm, leveling was reworked so they get Crusader Strike from level 1 baseline and at level 10, either Holy Shock, Avenger's Shield, or Templar's Verdict depending on spec (any of those make leveling much easier than it used to be).
Shadow Priests and Shaman. Even with the 4.0 talent changes that get them the fun abilities earlier, they both start out slowly and tediously, only to turn into one of the highest dps in the endgame if played well.
The "Luffa" boss gave the whole raid a particulary nasty debuff which was uncurable and did stack over time. The intent was to just heal through. However there was this level 40 quest reward item... You get the point...
Windwalker Monks start out with middling offensive capability, with them primarily relying on Blackout Kick and Tiger Palm to bypass enemy armor, then right before level 60 they learn Rising Sun Kick, which causes all enemies within 8 yards to take an additional 20% damage, and Tigereye Brew, which at 10 stacks from spending a total of 40 Chi on other attacks will grant a 60% damage increase. And when Tiger Palm, Rising Sun Kick and Tigereye Brew are used together...
Adding to Tigereye Brew's power, Windwalker's Mastery at level 80 gives you a chance to get an addtional charge with a base chance of 20%. If you can get enough Mastery from gear, gems, etc. you'll get 2 charges for every 4 Chi; the ability holds a maximum of 20 charges and you can use 10 charges at once, so you can pop it as soon as you get 10 stacks or wait until you get 20 so you can activate both halves in succession. Either way, the end result is pretty bloody.
Ultima IV has a quirky variation in the Shepherd class. The class itself (which has marginally better weapon and armour selection than the mage, no magic, and poor trap disarming ability) never really gets better, and to top it off you start off at a lower level and outside a demon-infested ruin instead of a city you could actually buy food in... but mastering the powers of the Avatar lifts restrictions on you regardless of class, like allowing you to equip anything or cast any spell, and due to how the party system is set up the party ends up overall stronger (you can't recruit the companion of your own class, and have to bring all recruitable companions with you at the end of the game, so you, who eventually can bypass the restrictions, being the Shepherd makes for better synergy).
Final Fantasy I has the Black Belt/Master; he starts off with access to crappy weapons and crappy armor (insanely weak knuckles/nunchaku and cloth, respectively), so he's pretty much useless at first. But his Absorb and Damage go up with level, so early on, you can drop the armor, and a little later, the weapons. By mid-game, he outdoes any other character on attack, and NEARLY every character on defense - he still has better dodge than the Ninja, even though the Knight can take more punishment. And at the end of the game? One hit kills the boss. God forbid you have a party of four of them.
In the original version of Final Fantasy III, the Onion Kid is your characters' starting class and almost entirely useless in every way compared to all the other classes. Except that at late levels (if you spend enough time), its stat growth suddenly becomes awesome, and it's the only class that can use the obscenely powerful Onion equipment set. This is even more prevalent in the Nintendo DS remake.
Edward from Final Fantasy IV is initially useless until you get better equipment for him, whereupon he becomes the fastest character in the game. If you level him to around 90-99, he gets the best stats in the game, maxing out almost every one. In the GBA remake, the harp you can earn for Edward to take through the endgame dungeon does extra damage against dragons, which many of the enemies there are, and even against non-dragons he goes so fast he can take two turns and do as much damage as the team's main tanks get in their one turn. The harp he gets in the post-game dungeon does extra damage against every enemy type; seeing 9999 damage becomes a common ocurrence. His only drawback is his auto-hiding when he's in critical health, which can spoil your healing rhythm, but which can also prevent a total party kill.
Edward has a similar arc of usability in Final Fantasy IV: The After Years. In his tale, he's mainly useful because the rest of his party (and all the monsters you face) are really low level; as a result, unless you take the extra time to grind the hell out of him, he'll start the last few chapters a good 10-20 levels below everyone else. And once he's on par as far as levels go, he's probably still going to have miserable attack power, and low HP. But, if you stick with him into the final dungeon, he gains a harp that has an extra attack bonus against everything in addition to being on par power wise with everyone else's weapons, he becomes extremely fast, and by now you've got enough cash to fill your pockets with X-Potions, making Salve a faster, more reliable (not affected by the Moon) healing than any White Mage, especially if you've got the accessory that doubles potion effectiveness. Add in the fact that his Bardsong allows free buffs and debuffs, and his Escape move lets him avoid any attack, and the Spoony Bard becomes damn useful.
The game's Freelancer and Mime classes are rather unimpressive on their own, but 'absorb' a mastered class's passive abilities and stat boosts, with the result that by the endgame, they're easily the best classes, since you can have a character with the highest boosts in every stat, using any equipment, and any combination of active abilities you want.
The Red Mage class, normally a Jack-of-all-trades class that's good in the beginning, gradually loses use as you go through the game. However, if you persist with the class, long after one would have abandoned it (its final skill level taking 999 points), you'll gain access to the absurdly powerful Dualcast ability, letting you cast magic twice per turn. The funny thing is that once you do this you'll never use the actual class again, as it has poor stats and forces you to waste one action slot for red magic spells.
The Chicken Knife. It becomes more powerful the more times you run from battle. Unless you are intentionally trying to power it up, it is an extremely weak weapon, but once you flee from enough battles, it becomes the most powerful weapon in the game.
Gau is seen as a Magikarp by most fans, simply because it takes forever to learn all his rages. (He's quite effective with just three, though.) With enough rages, he can absorb all eight elements, hit with any element half the time and a simple physical the rest of the time, or even use the rare Charm status on enemies. If that's not enough, he's one of two characters to use the Snow Muffler, the single best equipment in the game.
Strago is a Blue Mage, meaning he has to see the enemies' abilities to learn them. Unfortunately, he's a Blue Mage that you get late in the game, after you're well past the point where you'd normally run into the monsters using the blue magic he can learn. This means he's not a "set him aside, and he'll be good later" type, and more of a "If you want him to be useful, you have to go well out of your way and backtrack to get his abilities."
Relm has the best equipment, best magic power, but Sketch makes her frustrating to use because it basically uses an attack the enemy is likely immune to or absorbs with worse stats. But with Espers and the right equipment, Relm's awesome. Sketch also created easily exploitable bugs in the original SNES version of the game. It's not until fairly late in the game that you get to the point where it's exploitable rather than game-crashing, but once you find the right enemy group you can reliably fill your inventory with vast numbers of the most powerful equipment in the game.
The Cursed Shield - hits you with every status effect in the game, including Doom (which can't be blocked by a Ribbon, unlike the other status effects) - but take it into 255 battles, and it becomes the best shield in the game, negating or absorbing all elements of magic and avoiding most physical attacks, as well as teaching you the best spell in the game, Ultima (the only way other than the Ragnarok esper, which, incidentally, requires skipping the Infinity–1 Sword, and by extension, the ability to bet it at the Colisseum for an even better sword).
Final Fantasy VII: The Ultima, Shield and Full Cure materia. All do the same thing when initially equipped. Almost nothing, except muck around with your stats. Get them to their second level, though, and they give you a very powerful attack, a powerful defensive spell and the ability to heal a character and remove all status ailments from them. Nothing to sneeze at.
Enemy Skill is even more of one. It starts out with no effects whatsoever, and can't even be leveled up. If you know what enemies have what skills and how to copy them onto the Materia, it can provide access to most of the game's best spells two discs before those spells will even become available. Even once you get those spells, the Enemy Skill techniques are usually stronger, more convenient, or both. Some of the skills can be Lost Forever if you're not careful, but even without those skills Enemy Skill is the best Materia in the game in terms of raw versatility. Not bad for a yellow rock that doesn't do anything when you get it.
The Toy Gun from Dirge of Cerberus is pathetic at first, but can be leveled up into the ultimate weapon.
The Diablos Guardian Force reduces opponents' hit points by a percentage equal to Diablos' level. At its starting level 9, this is starkly unimpressive compared to other summons and spells; grind it to level 100, and it's instant death for anything with less than 9999 hitpoints.
The Cactuar Guardian Force. Its damage is calculated by the number of tens in its current level x 1000 (e.g. at level 43 it does 4000, at level 68 it does 6000). At level 100, it will do 10,000 damage to all enemies making it the second most powerful GF in the game. Unlike Diablos, bosses and other enemies immune to gravity damage are susceptible to this attack.
Some Celestial Weapons are harder to get than others, but all require you to go out of your way to complete a sidequest near the end of the game. All of them start out with an auto-ability that prevents the holder from gaining experience; you need to find two items to fully power them, at which point they triple the rate at which the wielder's Overdrive meter increases, increase the damage cap to 99,999, and gives up to a 100% damage boost based on the wielder's current health or mana, in addition to 2 other things that vary between weapons.
Tidus's Caladbolg comes with Evade & Counter and Magic Counter (in short, he will evade most physical attacks and counterattack everything thrown at him). It also scales his damage based on his current HP; more HP, more damage. It is also a strong contender for the hardest one to get; to fully power it, you must get a negative time in the Calm Lands chocobo race.
Lulu's Onion Knight gives her Magic Booster and One MP Cost (the short version is that all of her spells hit 50% harder and only cost two MP). Its damage scales with her mana instead, and since it only costs 2 MP to cast anything (and considering that almost nothing in the game has a Mana Burn effect), she will hit for around triple the damage she would do without it for next to no mana. However, powering it up infamously requires that you dodge 200 lightning bolts in a row; this requires a lot of patience and focus and decent reflexes.
In Blitzball, the Kilika Beasts starts out as the worst team but their players turn out to be the best with high stat caps at high levels. The Besaid Aurochs are roughly the same story. In fact, one of said Aurochs, Keepa, goes from lame-to-mediocre goalie to devastating shooter at high levels.
In the Final Fantasy X-2 blitzball minigame, Yuyui, recruited at Scout Level Max, starts off with 1 IN ALL HER IMPORTANT STATS. Not only that, she's very painful to train because her biorhythms NEVER go above 1, so you'll be eating up LOTS of Command Points just to let her rest. However, her max stats are all 99 (255 for those that go above 100), making her a total Game Breaker, given the opportunity to learn special skills like Corkscrews and Volleys.
Scholars start out as a wimpy, sub-par spellcaster that has low skill in all forms of magic, and unlike the magically similar Red Mages, Scholars have no real way of taking a beating or giving one. This begins to change at level 10, when the job has the ability to optimize either White or Black magic, raising the low D skills to a much more impressive B+ skill. It only goes up from there, as by the time Scholar reaches level 75, the job becomes a borderline Game Breaker with the sheer variety of magic it can use and the myriad ways it can be used. While many of the jobs feature in this trope, Scholars are the best example of it.
Red Mages are generally lack-luster White Mages until level 41 when they gain the spell Refresh that replenishes Magic Points when suddenly they become the pretty pretty princesses (Or to some others who play Red Mage, Buff/Cure whores) of Vana'diel. Their two-hour abilityChain Spell is almost completely useless until around level 40 when they gain more MP, a slightly better set of spells, and the ability to swap their current HP with their current MP.
Final Fantasy XII Revenant Wings rewards clearing a certain Bonus Dungeon with the Anastasia, a sword that has rather subpar stats compared to what Vaan can craft by then. Thing is, every subsequent time said dungeon is cleared, all of Anastasia's stats rise by 10, including Speed, which determines how fast a character attacks. Which means that after clearing it enough times, Vaan basically becomes a living blender capable of soloing most, if not all, of the game's levels.
Hope. For a good portion of the game, Hope is The Load. The player will schlep him around, cursing him for having such low hitpoints and attack power. Turns out, once you get him leveled high enough, he has the highest magic power of the entire party, and quickly outclasses Vanille as your best Medic once he learns Curasa and Curaja.
An entire role, the Saboteurs, suffer from this, as they start out slow and their debuffs aren't really gamechangers. Once you get to Gran Pulse, however, the game dumps a gigantic Difficulty Spike and suddenly Deshell, Deprotect and especially poison make things so much easier. Then Vanille (likely your main Sab) learns Death which, unlike in previous FF games, actually works on things now.
Final Fantasy XIII-2: Just about any monster ally with the "Late Bloomer" trait is a case of this, but none more so than Twilight Odin. Starts out weak, at Level 1, and doesn't really get any significant stat gains until Level 80. Once he gets there though, his stats skyrocket, especially Strength, which tends to go from the low 400s to nearly 1000 in the space of only 10 levels. He's also one of the few non-DLC monsters that can have the full 6 ATB segments. Granted though, it costs roughly 260 Crystals to get him there though, so many consider him Awesome, but Impractical, especially since his attack speed is much slower than most other high-end monsters and having 6 ATB segments doesn't matter much when he poses long enough after every 4 hits that his ATB bar is already half full by the time he can resume attacking.
Cactuarama, a well-hidden Medic, starts out horrendously underwhelming, with low Magic and HP and the inability to learn any advanced Cure spells naturally. However, its Feral Link, Uplift, not only restores HP to everyone, but is also the only way to bestow the Reraise buff. Good infusions and the right materials will make Cactuarama a force to be reckoned with.
The Calculator is the slowest class in the game, and thus the slowest to develop its skills. Once the class is mastered (and all Calculatable spells learned), the skills learned from the class make it the best secondary class in the game, to the point where one well-rounded Math Skill user virtually guarantee victory against absolutely anything the game can throw at you, and the rest of the team may as well stand around using Accumulate.
Closely related, the Bard and Dancer classes were extremely weak. But their abilities happen so frequently (sometimes two or three times per command action), and they get experience each time their abilities activate, meaning they both have a habit of power-levelling. Combining these Skills with a Calculator results in game-crushing power in a very small number of fights.
A bonus character you can recruit is Cloud Strife from FFVII, who starts off way back at level 1, even though you're relatively far into the game when he can be recruited. Even after being leveled up, he probably doesn't seem like anything special; he's a good physical fighter, but you've got better ones, especially since his special attacks require him to use the fairly weak Materia Blade. And many of his special attacks, including almost all the powerful ones, are too slow to be really useful. But not all of them; Finish Touch fairly quick, and it's a real Game Breaker: it has 100% accuracy, and inflicts a random selection of Stop, Petrify, or Instant Death. Even the least desirable outcome, Stop, puts an enemy out of action long enough for another character to take them out.
Ramza's Squire class is also like this, only it gets more advanced depending on how far you are in the game. In chapter one, the only difference between it and the standard Squire is that it can equip robes but not axes and it gets the "wish"note which heals HP at the cost of inflicting half the healing on Ramza, while Ramza likely has the HP to take the blow better than whoever is being healed, but it's inferior to almost any other option for healing, but acceptable in a pinch and "yell"note increase speed by 1, actually somewhat decent abilities. In chapters two and three, Ramza's Squire gains a few new skills, better stats, and the ability to equip heavy armor and shields. By chapter four, however, Ramza's Squire class gains an ability that lets him temporarily boost all of his stats, has some of the best overall stats in the game, can equip Knight Swords (among the strongest weapons in the game), and can learn Ultima, making it one of the best classes in the game.
Morphers in Final Fantasy Tactics Advance shapechanged into monsters instead of learning skills. Problem was their powerlevel corresponded to the power of the monsters you had captured, meaning early game captures were useless fairly quickly. But if you invested huge amounts of money in feeding your captured monsters they would grow to ridiculous sizes & grant these ridiculous (read:999) abilities to the party Morphers.
Final Fantasy Tactics A2 — The Sequencer Knightsword and the Peytral Armor can be obtained pretty early in the game, and usually they'll start off fairly weak. However, the sword and armor add a point to their respective attack and defense when an opportunity command is utilized in battle, and they can accumulate up to 99 points to get a total of 131 attack and 127 defense — compare the next best Knightsword and Heavy Armor, at 72 attack and 58 defense, respectively. This crosses over into Game Breaker in that your characters don't have to equip them to get the points, and it works retroactively, so if you were to work up to 99 opportunity commands from the get-go...
Onion Knight works quite similarly to his original Final Fantasy III incarnation. His default attacks are weak and hard to connect with, but as he levels up he gains the ability to chain them into other attacks and becomes highly versatile.
Firion. At the start, he has exactly one HP attack (i.e. how you kill things, for those unfamiliar with the battle system): a projectile of medium speed with a charge time. As he levels up though and masters his Bravery attacks he learns the ability to chain them into Double Trouble, and learns the HP attacks Weaponsmaster and Lord of Arms, turning him into a mid-range god.
Named for the Pokémon Magikarp, which has horrible (but not the worst) stats and can only learn four moves outside of eventsnote Splash, Tackle, Flail, Bounce - with Flail being introduced in Generation II, and Bounce first becoming available to Magikarp beginning in Pokémon Platinum (which was actually a paltry two moves at the time of its original debut appearance in Pokémon Red and Blue), one of which does absolutely nothing, and cannot be taught anything else from TMs, HMs, or the Move Tutor. However, it eventually evolves into Gyarados. While it still has enough weaknesses to avoid being aGame Breaker, it remains as one of the most powerful and versatile creatures in the game (aside from those in the Uber tier). It's still a staple in many competitive players' teams, and has recently gained a Mega Evolution, becoming even stronger. Interestingly, Magikarp can evolve at level 20, which is actually much earlier than most final evolutions with comparable stats, but doing so is still a pain because the damn thing is so weak.
As strange as it may seem, the highest-Level wild Pokemon that can be captured in the franchise is a Magikarp. In the Resort Area of Pokémon Platinum, a guy tells you about the "King of the Pond", hinting that you might catch it if you use a Super Rod. He's telling the truth. It is possible to catch a Lvl 100 (the highest legitimate experience level for a Pokemon) Magikarp in this area using the Super Rod if you're very lucky. You don't get any real award for doing this and the Magikarp is still rather useless (it can't evolve), but it is interesting.
Even more ironically, Magikarp is harder to find in later games (likely because this Trope is no longer a secret). In the Gen V games, it isn't even native to Unova; the only way to get one in Black and White, other than trading or transferring, is via the Magikarp Salesman that you encounter after the main storyline. You can still do that in the sequel, but you can also catch one after the main storyline when Professor Juniper gives you the Permit, in which case Skyla will fly you to the Nature Preserve, a place where there are lots of Pokémon not native to Unova. (The Nature Preserve is not considered part of Unova.) In Gen VI, you can fish for them in Central Kalos with the Old Rod; attempting to do so in the Coastal region gives you Luvdisc instead, which actually arepretty worthless as Pokémon (but are a good source of Heart Scales).
On average most Bug-type Pokémon are like this. They're very weak starting out, on average get a middle stage with mildly better defensive stats, and then an early 3rd form with higher damage. The only downside to them is that because they evolve so early on, their overall stats don't match up to later and more difficult to obtain mons, due to their gimmick as a Crutch Character.
The main thing Feebas has going for it is that it can learn TMs. Magikarp's only non-level or event-learned move is Bounce, which is Tutored.
The Prism Scale that first appears in Unova bypasses the Guide Dang It and allows Feebas to evolve on a trade. Amen. Additionally, although rare, wild Milotic can be caught in Unova.
All of the pseudo-legendary Pokémon are hard to catch, evolve at high levels and their pre-evolutions have poor movepools and stats. However, if you level them up, they are the strongest Pokémon outside of legendaries and Slaking.
Beldum can attest to Level 20's awesomeness, as it goes from a ridiculously hard-to-catch floating leg that can only learn Take Down, an average powered move with poor accuracy that damages the user, to Metang, which becomes the defensive and powerful Metagross at level 45.
Larvitar is a teensy greenish mon found at level 20 in Mt. Silver, the final area of Gold and Silver. It's sluggish, relatively weak, and has bad typing (Rock/Ground), though it learns a small handful of semi-decent moves. Its evolution, Pupitar, is only slightly better. But when it evolves into Tyranitar, it gets massively boosted stats, better typing (Rock/Dark), and a better movepool.
Out of the pseudo-legendaries, Deino, is particularly notable because it evolves much later than the rest - its evolution levels are 50 (you can get Salamence, Metagross, and Garchomp, other pseudo-legends, by this level) and then level 64, the highest evolution level of anything in the entire series. What's more, Deino and its evolved form Zweilous have an ability that lowers accuracy, making them unreliable to use. But when Zweilous evolves into Hydreigon, watch out!
Gen VI's pseudo-legendary, Goomy, is another extreme example. When you first catch it, its stats are comparable to Com Mons, and its movepool is lousy. Even the Pokédex says it's the weakest Dragon-type ever. If you stick with it, however, it eventually evolves into Goodra, which has staggering Special Defense and is the most adorable dragon ever.
The move Return is this. It starts out rather weak, but since its power is tied to your Pokémon's Happiness stat, which increases with leveling up, winning, and even walking around, you can hit its max power of 102 eventually. Teaching it to a Normal-type Pokémon gives a +50% Same-Type Attack Bonus (STAB), putting its maximum base power at 153—more powerful and accurate than a STAB-less Hyper Beam or Giga Impact without the recharge turn.
Abra is hard enough to catch, and when you do catch one, it has one move...that lets you run away from battles. Unless you have TMs, you'll put up with some bait and switch Level Grinding before it turns into a Kadabra, then broken (in Generation I, at least) and speedy Alakazam. Note that it can reach its final evolution just after evolving at Level 16. Then you find a piece of Alakazite and go to town.
While a complete list would fill the page, there's also Slakoth. Poor stats and it only acts every other turn, but at Level 16 it evolves into the psychotic Vigoroth—and after that into Slaking, which goes back to only acting every other turn but has one of the highest Attack stats in the game. Slaking's stat total actually matches the godlike Groudon and Kyogre, and is the highest of any non-legendary Pokémon in the game.
The Slaking line might actually be a subversion, depending on the player's battle style. Some trainers prefer to evolve their Slakoth into a Vigoroth and keep it that way, as Vigoroth is a Jack of All Stats and it can act every turn. Vigoroth's ability also shields it from being put to sleep.
Other particularly notable Pokémon include Tynamo, a cute little electric eel introduced in Black and White which has crap stats and four okay moves until it evolves at level 39. Additionally, it takes more experience per level-up than most Pokemon at the same level as it, making it a great pain to raise to level 39. However, upon reaching level 39 it starts getting good (and fierce-looking), and even better still when you use a Thunderstone on it. All three members of the Tynamo line have no weaknesses too due to Levitate removing their sole weakness to Ground, which makes up for Tynamo being rather weak.
Combee starts off knowing three moves and its stats are lousy. Also its ability is only useful for producing Vendor Trash. But if you can get your hands on an elusive female and raise her up to level 21, you'll have yourself a Vespiquen, a combination of a bee and a battleship with a touch of European royalty. Not only are her stats better, but she has a much wider variety of attacks to choose from and has three signature moves each revolving around controlling swarms of Combee and has good abilities to choose from.
Larvesta begins with average or poor stats in everything except Attack, which goes to waste when you see that its evolution, Volcarona, has massive Special Attack instead. It doesn't even evolve until Level 59, but if you do, it gets a mountain of Special stats, Speed, and Quiver Dance, which boosts all three of those stats by one level. And you can catch a Volcarona at level 70 in the Relic Castle after you beat Ghetsis (or level 35 after defeating Clay in the sequels), so have fun with that. It should definitely be worthwhile to get your hands on one.
Unfortunately, there are no other wild Volcarona or Larvesta, so if the one in the Relic Castle doesn't have the right Nature for your liking, the only other way to raise one is from an Egg, which means level 1.
Zubat as well. The only moves it has up until Level 16 (12 in later generations) are Astonish and Leech Life, and in the case of Red/Blue and their remakes, almost every Pokémon in the early game is either immune to the Ghost-type or resistant to the Bug-type, so you'll have a time raising its levels until you can get to Oddish and Abra. And then even when it learns new moves, it gets Supersonic, an unreliably-low accuracy move, and Bite, which doesn't benefit it much until Generation IV since it's a Special attack. By the time it learns a good move, Wing Attack, it's already practically a Golbat, effectively doubling its usefulness after the tough early stages. Then it gets Confuse Ray shortly after, and may potentially become Crobat soon...
Togepi starts out as a typical baby Pokemon: bad stats (aside from surprisingly good defenses), bad typing, and a less-than-inspiring movepool. If you get its happiness to max, it evolves into Togetic, which is...better. But, starting in Gen IV, if you use a rare Shiny Stone on Togetic, you'll get Togekiss, which gets a major boost to its stats and can learn a great variety of moves. If you have one with the ability Serene Grace (makes added effects like flinching happen more often), moves like Ominous Wind, Ancient Power, and Air Slash become quite deadly. And thanks to the Fairy hybridization in Gen VI, the thing can effectively nul-STAB Garchomp!
Ralts is the weakest Psychic-type Pokémon as of Generation V and catchable in Generation III prior to beating the Elite Four. It's only catchable on Hoenn Route 102 - which is the third route the player visits. It has a 4% chance of appearing and is about level 5 at best, learning only one offensive move before evolving at level 20 - and it's not even evolving into something equivalent to Gyarados, instead becoming the THIRD weakest Psychic-type... on reaching level 30, it becomes a Gardevoir, the second strongest Psychic-type - and in the Top 20 of Pokémon overall (and stated in the Pokédex to be even capable of creating a black hole, despite the lack of it in-game).
From Generation IV onward, male Ralts and Kirlia have the option of evolving into Gallade. His stats are equal to Gardevoir's, but his attack stats are inverted. He also gains the Fighting type and is able to learn a number of physical movesnote Had at least one for every type except Dragon in Gen IV, this is fixed in Gen V with Black 2 and White 2 Tutors where he receives Dual Chop., along with the support moves that the rest of the Ralts family can learn, leading to a fairly unique and powerful Pokémon. Plus, you can get him as soon as Ralts evolves at level 20.
Seedot from Ruby/Sapphire/Emerald starts out as one of the worst first evolution Pokémon in the game. The only slightly useful move it has, Bide, uses the attacks that the opponent inflicts on it and then dishes it back two or three-fold. Hard to use early on and only gets better when it evolves into a Nuzleaf at level 13. Though if you want to make it really effective, you need to use a Leaf Stone to instantly evolve it into a Shiftry.
Magnemite was pretty weak as an Electric Pokémon in Generation II - it started with Thundershock, but that was the only damage-dealing Electric move it learned, even after evolving into Magneton... that is, until level 45, when it learned Zap Cannon.
However, take it to Sinnoh's Mt. Coronet, Unova's Chargestone Cave or the Lumiose Badlands and level it up, and it'll evolve into the mighty Magnezone, which has amazing Special Attack (highest of all Steel-types and Electric-types) and Defense (highest of all Electric-types). Its evolutionary line doesn't learn Zap Cannon until much later to compensate, but it can still take out whatever doesn't resist or nullify its moves.
Trapinch has a huge Attack stat, and nothing else, being one of the slowest Pokemon from any generation, and a particular pain in the ass to level up. But if you give it enough patience, you'll be rewarded with Flygon, the original badass Ground/Dragon type that was around before Garchomp became all the rage.
Several abilities and moves also fall under this. Slow Start halves Speed and Attack for five turns, making the one Pokemon that has that ability (Regigigas) nearly useless until the ability runs out, then Regigigas starts hitting like a tank. Moxie allows Pokémon to boost their Attack every time they knock out an opponent, turning decent Pokémon into monstrous attacking machines. Any stat-boosting move in the game also can potentially turn even the weakest of Pokémon into monsters that legendaries cower at.
Then there's Moody, an ability that increases a random stat at the end of every turn, and the only ability to be banned by clause.
Appropriately enough, it's possible to get a Gyarados with Moxie, giving a Magikarp Power ability to the trope namer.
A lot of mons that evolve via evolutionary stone don't learn their best moves until high levels, and only the pre-evolutions can learn them, which means you have to drag them around for quite a while before getting said moves. But once they've evolved with those moves, watch out!
The humble and tiny Eevee could be this. It's on the lower end of the "middle of the road" spectrum, however with so many ways it can evolve and almost each one excelling at a particular role, you can tailor it to whatever role in the party you want. Oh, and it's also still very cute.
Shroomish, a silly-looking walking mushroom (no, not thatwalking mushroom), starts with poor stats in everything but its defenses and HP. It evolves pretty early, but that's not what you want. If you have the patience to keep cancelling the evolution and dragging it around until it reaches level 45 (in Generation III it was level 54), it learns Spore, which always causes sleep. Pretty useful, since the only other possessors of said move aren't that good in regular combat. Then, once evolved into Breloom (a slightly less silly-looking mushroom kangaroo boxer), it gains a ton of Attack stats (from 40 to 130, the most of any non-legendary Grass-type), the Fighting type, and plenty of good moves. Plus, its abilities are good- either it heals from getting poisoned (works well with a Toxic Orb), inflicts status ailments when hit, or boosts the power of moves with 60 base power or lower by 50%. It may be a bit of a challenge to use and is kinda slow, but it's worth carrying it around for 22 levels more than it needs.
Tangela, a Junk Rare prior to Generation IV, has great Defense and Special Attack... but nothing else is really notable. Its movepool isn't that great either - a common situation for Grass-types - consisting of some weak offensive attacks and some status moves. But once it learns Ancient Power, a decent Rock-type attack that allows it to cover its weaknesses (and has a chance of boosting all its stats at once), it evolves into Tangrowth, a powerful tank with high Defense and HP, and good offensive stats to boot. Plus, its movepool gains an upgrade, increasing its effectiveness.
Litwick, a Ghost/Fire-type from Generation V, has terrible stats and doesn't evolve until level 41. However as soon as it does, it can be evolved again into Chandelure which has the second-highest Special Attack of any non-mega, non-legendary, less than 10 points shy of Mewtwo.
Porygon was yet another Junk Rare back in the first generation, with poor defenses and Speed, but a somewhat decent movepool. You have to trade the thing twice, using two different items, to get it to evolve into Porygon-Z, which has a crapton of Special Attack and good movepool... but worse defenses than Porygon2. This works in Porygon2's favor however, as it allows it to utilize Evolite in order to tank the likes of Garchomp and even Rayquaza.
The "Citizen Snips" set mixes this trope with Gradual Grinder. A Drapion with maxed Defense and HP, Acupressure (sharply boosts a random stat), Rest (sleep to heal and cure status), a coverage move (usually Crunch) and Battle Armor (negates buff-ignoringCritical Hits) will have a hard time doing damage if you send it in cold, and lacks utility for a Stone Wall. However, some stalling and a little luck with Acupressure early on will result in a Pokémon that effortlessly dodges the few attacks that don't glance off it and drops most opponents in one bite. If Snips can get in an Evasion or Special Defense boost before the opponent can outdamage it or force it to switch, it will murder the entire team.
Other Video Games
In the original Digimon virtual pets, the amount of care taken in raising your pet determines its evolutionary path, with bad caretaking resulting them digivolving into the pathetically weak Numemon, a bug-eyed slug-thing who attacks by throwing its own excrement. However, raising Numemon with perfect care will result in it Digivolving into Monzaemon, a giant teddybear who is capable of defeating any other Digimon with extreme ease.
In the first Digimon World game for the Playstation, you didn't even have to raise Numemon well, just finish the Toy Mansion to get the Teddy Bear Costume; then you can spam all the Monzaemon you want.
Dungeon Explorer, a Gauntlet-type game for the TurboGrafx-16 console had the bard - a weak character that did low damage and had crappy spells (one of them changed the background music.) However, midway through the game he could be transformed into a hermit - the most powerful character in the game.
The first fighter you get in Freespace 2 is pretty average — not too fast, not too strong, can't carry a lot of missiles, moderate weapons compatibility and later on is usually passed over in favor of Interceptors or Assault Fighters. It's a strategic pick in multiplayer, however, because it's the only fighter that can carry the Helios antimatter torpedo. Most bombers can't even equip that weapon, which is capable of destroying a cruiser in one shot.
In the Playstation survival horror game Hell Night (also known as Dark Messiah outside the U.S. - not that one), you have a choice of four partner characters that can accompany you through the game. If you get attacked by whatever monster is currently stalking you at the time, you die, unless you have a partner, in which case they take the hit for you and die in your stead. You can then get one of the others if you're in the right place at the right time. The first partner you get has no weapon but can sense the location of the monster on your map, while the other three cannot; however, they do have weapons (with limited ammo, of course) that can stun the monster long enough for you to get away, but not kill it. If you keep the first partner (a teenage schoolgirl named Naomi) all the way through the end of the game, in the final areas of the game she has a random chance to say, if you spam the "talk to partner" button while the monster is approaching, "I wish... I wish you were DEAD!", which stuns the monster just like an attack from one of the other partners would, and can be used an endless number of times.
The second sword Lann smash in Vindictus is fairly useless at low skill ranks, with a small area, little damage, both only mitigated by a moderate knockdown. Once you max the skill however, the damage is improved immensely, the moderate knockdown becomes a high knockdown, and it gains a secondary dash attack, making it one of the more useful smashes for mobile bosses.
Despite being a mandatory character, Ibis Douglas in Super Robot Wars Original Generation 2 is like this. Her primary Humongous Mecha is potent, but her stats are so low she lags behind... until you get around level 50, when her stat-gains start going out of control and she ends up the best character in the game. However, unlike many, this is frequently alluded to in-game, with multiple references to her "potential."
In Alpha 2 she only gets a massive stat boost as part of a plot event in stage 32 (namely finally shaking off her self doubt and loathing. Before then leveling her to max won't help her any. In fact weak Ibis and strong Ibis have separate character data. Strong Ibis has a few different abilities (and loses a useful ability weak Ibis had that helped keep her alive though you no longer need it at that point) and her outfit in game is different.
Gundam 0083's Kou Uraki's a more reasonable example, combining with Took a Level in Badass. Kou starts out underleveled and in an inferior machine. Between leveling up and getting the GP-03, you realize problems with him in the past didn't come from himself, but simply his machine.
The other traditional example in the later games is Boss from Mazinger Z. He starts off in a terrible machine with low stats and little value except a cheap repair cost. However, if you level him high enough (usually around 80) his subpilots get a ton of incredibly useful spells for dirt cheap and his stats go through the roof. In addition by this time you'll usually have Mazinkaiser, which means that Boss can get out of his terrible machine and upgrade to Mazinger-Z. The trick is that level 80 is absurdly high in a game series where the final bosses rarely get above the mid-70s. There are ways to level him up that high, but they're generally inefficient or a lot of trouble.
The Borot itself is often a kind of Magikarp Power - while it starts out with terrible stats and no ability to hit airborne enemies, its weapons are extremely cheap to upgrade and become stronger than those on Mazinger itself. With four part slots, you can easily buff up its stats and give it flight, fixing its anti-air issues.
Turn A Gundam is the most infamous one. In any game you get it it starts out underpowered, but after it unlocks some of its attacks and abilities, (like flying, moonlight butterlfy, HP regen) it's a powerhouse. Also Loran's stats start jumping when he passes around level 50.
Also in Alpha gaiden, all the originals are pretty much useless. Except Ryusei, who starts out as the worst because him being in an MP mecha(unless you're on easy by the stage you first get him, then he starts in a MP Grungust. This trope is magnified if you're on hard where he gets a Gespenst, he gets a Huckibein MKII on normal)Most people don't use him because, 1. You only get him for like 2 stages before the time jump and you get him back pretty late into the game. However, he has a VERY high melee stat from the start, and once he starts getting into the higher levels he learns incredible skills (his starting Psychic abilty can go up to the max level and he knows Guts, support and Sheild Def), a wonderful spirit list, and his stats start jumping up, he becomes one of the best pilots in the game. But he's still so-so until he gets R1-Kai, which has one of(if not the best)barriers, the TK field ability, and it has GREAT stats.
For Zero in his own saga, his weapons from the first two games all apply. Frequent use of said weapons increase their abilities (the Z-saber, for instance, unlocks skills and even enables a Charged Attack with each subsequent level). There's also the Platforming Pocket Pal from the fourth game: it has 21 different abilities that can only be unlocked by feeding it E-crystals, the Reploids' and Energy Beings' equivalent to a power food.
In MOBA (Massive Online Battle Arena) games such as Heroes of Newerth, Defense Of The Ancients, and League of Legends you have champions that are very frail and weak early-game but are unstoppable monsters late game because they scale really well with levels and items. These are called "carries". If the enemy team does not stop them from progressing to this stage, carries can win 1v2, 1v3, and sometimes even 1v5 fights.
Shujinko, the "deceived" hinted at in Mortal Kombat Deception's title, has a whole story mode to unlock him. Once you've done that, you have to go through the realms to get his other moves, without anyone to give you hints. But these moves are the best moves from the other fighters, so it works out well.
Special weapon 5 from Zanac. It starts off as a single small orb which slowly goes forward and them back. However, it ends up as a laser which goes through almost everything and is one of the most damaging weapons and won't even richoet off the capital ships.
The PSP game Dungeon Maker 2 provides you with a pet who can change into a number of different monsters if you have their "memory." The memories for stronger monsters are found later in the game, but they all start at Level 1 (which is no more powerful than it sounds). This effectively makes all forms other than Human Ally a Magikarp, and also gives Magikarp Powers to players willing to level up a number of them just to learn their transferable abilities.
Sol Forge has several cards which start out extremely weak at level 1 but become incredibly powerful at level 3. Chrogias, Scorchmane Dragon, and Scrapforge Titan are examples.
Mount & Blade: The Peasant Woman unit can only be recruited if they are rescued from another army's prisoners, they're abysmal fighters, and all they have on them are puny little daggers. Their chances of surviving battles are slim. However, if they grow in experience, they can end up becoming Sword Sisters. Sword Sisters are adept at combat and equipped with good swords, heavy crossbows and plate armour. They're on par with Mercenary Captains. Girl power.
Anime and Manga
Mako Mankanshoku from Kill la Kill is actually remarked on in-universe in this regard. She's completely weak and uselessnote a computer analysis' Stat-O-Vision gives her zeros in every category, but give her a Goku Uniform of the same type used by every club captain, and she's suddenly a master of combatnote the computer analysis' Stat-O-Vision gives her 9999 in every stat except intelligence.
The most basic ability granted to Issei Hyoudou from Highschool Dx D from his Sacred Gear is Boosted Gear, which doubles his power every ten seconds. It's explicitly stated that this effect is enough to let him trump God if he gets worked up enough. However, this depends on Issei staying alive in combat for that long, when he starts the series so talentless the first few doublings have barely any effect.
In Chess, the ubiquitous and slow-moving pawn can be promoted to a stronger piece (usually the queen) if allowed to move all the way to the other side of the board.
There are numerous examples in the Shogi (Japanese chess) family. In Tenjiku Shogi, there's the Drunken Elephant, which can promote into, essentially, a second king, allowing you to survive your first king's death, and the Water Buffalo, which promotes into a Fire Demon, insanely useful because of its ability that allows it to capture a ton of enemy pieces in one move. There's also the Deva in Tai Shogi, which can only move one space in certain directions, but promotes into the Teaching King, which, depending on how you interpret the rules, can move as a Free King (a chess Queen) and with 3-step Lion power. (Lion power normally allows a piece to make two separate one-step moves, each counting as a move in its own right, in one turn. In this case, three.) Pawns don't get a lot of love though.
In Chinese Chess, the soldier can only move vertically much like pawns in Chess. Once it crosses the "river" into enemy territory it can move and capture pieces horizontally as well.
This was so prevalent in Dungeons & Dragons that it got its own trope: Linear Warriors, Quadratic Wizards. At low levels, a Wizard quickly runs out of spells (and thus, effectiveness) while a Fighter can deal consistent damage all day long. However, if you keep at it then the Wizard gains enough spells to hold their own, and access to a vast variety of offensive and utility spells that drastically increases their power and versatility. Then in the mid-game they start learning "save or die" spells. By the end-game, Wizards are on-par with Physical Gods.
Fourth edition made Wizards more balanced, with them more useful at level 1 and less broken at high levels. There is still the uber-broken Orb of Imposition optional class feature, however, which still exhibits this property.
Healers (the Miniatures Handbook class, not the character type) are generally considered to be useless - until 17th level, when they get Gate, one of the most powerful spells in the game. However, many other casting classes get Gate by that level, which leads to the Healer going from "Not as good as a Cleric" to "Still not as good as a Cleric". The infamous Truenamer class also gets Gate at level 20, but the class was so badly-written that it takes a dedicated Munchkin to even keep it alive until level 20.
The Samurai class from Complete Warrior is an unintentional example. It's strongest feature is the Samurai code of conduct, which makes you lose all your abilities if you break it ... because the class is so weak that losing it actually makes you more powerful! Specifically, breaking this code of conduct when higher than level 11 allows you to switch 10 class levels to the far-superior Ronin class.
The Bard in First Edition required that you dual-class three times, and given how complicated dual-classing was then (each dual-classing would restart you at first-level), this was no mean feat. However, upon taking your first level, you then gained all your old fighter skills, all your old thief skills, druid casting, music that boosted allies and automatically charmed enemies, lore powers, and magic item-based powers. And you've got 23 levels to go...
The Fochlucan Lyrist, a prestige class in 3.5, was an attempt to update the original Bard's Magikarp Power. The easiest way to join was to take four levels in Bard, four levels in Druid, and two in Rogue, a horribly disorganized build. However, the Fochlucan Lyrist advanced arcane casting, divine casting, and bardic music, and received six skill points and a warrior's Base Attack. Unfortunately, the build it worked off of was so hideously weak that even such a powerful class could do little more than damage control; at full advancement, the Lyrist's main components would both be six levels behind.
Magic: The Gathering has a number of cards that function like this, starting out average or even worse than average in some cases but becoming very powerful when some condition is met.
The Kamigawa block had a number of "flip cards" which are fairly weak, relatively useless creatures when first summoned, but can be "flipped" (rotated 180 degrees) when certain conditions are met, generally becoming a powerful legendary creature. The conditions required to flip these cards are sometimes quite easy. Student of Elements, for example, becomes Tobita, Master of Winds as soon as it gains flying, a task fairly easily accomplished with blue spells. Others are considerably more difficult to flip, but the results are worth it. For instance, Bushi Tenderfoot must first contribute to the death of another creature to flip, but as a puny 1/1 it isn't likely to kill much of anything without help, and will surely die if sent into combat without some sort of outside boost or protection. However, if you do manage this feat that puny Tenderfoot becomes the immensely powerful Kenzo the Hardhearted, who is capable of dishing out a whopping 10 damage to an enemy creature in combat.note To put it into perspective: a normal nonmagical human with a sword hits for 1. A grizzly bear hits for 2. A hill giant hits for 3. Most dragons hit for 5 and up. So a creature dealing 10 damage by itself is like two dragons mauling something at once.
The recent Eldrazi set has brought along creatures that gain 'Level Counters' when ever you pay to do so. Their stats increase takes a while and it takes up resources that could be kicking out more cards instead, but some of them get REALLY good powers at max level. For example Lord of Shatterskull Pass - Wow.
The latest set, Innistrad, introduces double-faced cards and the transform mechanic. Most of them are werewolves but one in particular, Ludevic's Test Subject, is an egg. It has zero attack power, and is in fact completely unable to attack. However, once you use it's ability to give it five "hatch" counters, it becomes Ludevic's Abomination, a 13/13 creature with trample, which is much better for attacking.
The Serra Ascendant starts out as a 1/1 with lifelink. If you manage to get your life total >= 30 (you start with 20) and keep it that high, the Serra Ascendant becomes a 6/6 creature with flying and lifelink. Naturally, Serra Ascendant is a solid addition to any deck that specializes in life gain.
Jace's Phantasm is normally a puny 1/1 flyer. It becomes a respectable 5/5 flyer (making it as powerful as the average dragon) if an opponent has ten or more cards in his or her graveyard. Conveniently, a lot of blue cards (especially those related to Jace Beleren like the Phantasm) force players to discard cards.
Tuktuk the Explorer starts out as a measly 1/1 with haste that costs three mana to summon. If he dies, he is replaced by a legendary 5/5 goblin golem artifact creature called "Tuktuk the Returned". Since the opponent probably isn't going to be in any hurry to kill Tuktuk for you, you'll need to find a way to hasten his demise yourself.
This is seeing a return with the Theros block's Heroic mechanic. Heroic creatures gain a special effect when you target them with a spell, usually placing +1/+1 counters on them. It is quite easy to turn a 1/1 Favored Hoplite into a complete monster that simply doesn't take damage and can bulldoze through enemy defenses.
Primordial Hydra starts out relatively weak, with power and toughness equal to the X value when summoning it, which could conceivably be as low as 1. Every turn, though, it doubles its power and toughness, which, through the power of exponents, can make it unstoppable in, at most, 5 turns, and even less if extra mana is used when summoning it.
Yu-Gi-Oh! has a similar monster group known as the Geminis, monsters that are treated as effectless Normal Monsters while on the field and in the graveyard, but if you're willing to waste a Normal Summon or card effect on them, become powerful Effect monsters. Considering that Normal Monsters themselves are Lethal Joke Characters requiring a proper build with the right cards to become powerful, and most of said cards can be used with Geminis, and well...you do the math.
Longtime players may remember Maha Vailo, a Level 4 monster with mediocre stats (1550 ATK/1400 DEF). On its own, it was useless, but its special ability allows it to gain an extra 500 points of attack power for every equip card given to it. A simple Malevolent Nuzzler or Horn of the Unicorn(both of which provide a 700 ATK boost) now boost Maha's ATK by 1200, and the fun doesn't stop there. With the right equips, it could have an ATK over 4000, and easily be strong enough to take out more than half the opponent's life points in a single shot. Bear in mind that this is a game where most high-end monsters have ATK power in the range of 2500-3000.
The strongest it can get? Five Monsters out including itself (easy using Scapegoat), three United We Stand, two Mage Power, and Luminous Spark. That would give it 22550 ATK - for comparison, Five-Headed Dragon, the physically strongest Monster out there, has 5000, and starting Life Points is 8000. Don't screw with Maha Vailo.
It now has a Spiritual Successor in Morphtronic Videon (1000 ATK/1000 DEF), which gets 800 per equip card when in attack postion. Using the above cards, it can get 23500 ATK.
Mataza the Zapper - An effect monster card with a pretty dainty 1300 ATK and even worse defense. The catch? He can attack TWICE during the battle phase. Helloooo equip cards! Plus, he is immune from having his control switched, so you can't use cards like Enemy Controller on him and works effortlessly into any warrior based deck.
Armed Samurai - Ben Kei gets an additional attack for every equip card you put on him. With, say, Mage Power and Axe of Despair, he'll hit three times for 2500, very nearly enough to completely oneshot a player. Yes, there have been decks built around disabling your opponents magic and traps for a turn, then summoning this guy with three equip cards and winning the game.
Similarly, there's the combo with Chimeratech Overdragon, which is a Fusion Monster with ATK equal to 800 times the number of Fusion Materials. This can be combined with a card that lets you discard, from your deck, the Fusion Materials for one monster, and another card that lets you remove from your discard pile the Materials for a Fusion Monster and Summon it. Then you can use a card (Limiter Removal) and double Chimeratech's ATK, possibly leading to something along the lines of a 36000 ATK monster that can attack 20 monsters each turn.
Yet another example might be the LV monsters. While they generally start as something like a LV 3 1000ATK monster, when conditions (Ranging from as simple as surviving until the next turn to directly attacking your opponents life points) are fulfilled they level up, bringing out the next level, until they reach their final forms, with 2700 ATK or more and powerful effects such as negating all Magic cards or destroying all your opponents monsters by discarding a single card.
These also were a subversion- only the highest levels were required to be summoned by effect (mostly) so you could often just skip the lowest stage by playing the middle one first.
You could also consider the Batteryman AA strategy an example of this. Batteryman AA (LIGHT Three-star(I think) 0 ATK/0 DEF) is a monster that for every Batteryman AA on the same player's field (meaning your opponent's don't count), they all gain 1000 ATK each if they are all in ATK position and 1000 DEF each if they are all in DEF position. The thing is, getting and keeping your Batterymen on the field would normally be a challenge. But with Inferno Reckless Summon, a card that when you special summon a card, your opponent selects a face up monster on their side of the field, and they summon all the cards of the same name from their hand, deck and graveyard to the field in face up ATK position, but you also do that with the card you special summoned. That mean if it was Batteryman AA, you get three 3000 ATK monsters on the field, ready to attack. Then, if you use the card Shot Circuit, whose effect is if you have three or more "Batteryman" cards on your side of the field, destroy all the cards on your opponents side of the field, you then deal 9000 direct damage to your opponent's life points, and they only start with 8000, thus winning the duel with a monster with 0 original ATK and DEF.
Also consider monsters who gain attack equal to the number of cards removed from play. This troper once saw Inferno Tempest (remove almost all monsters each player has from play when you take at least 3000 damage from one attack) combined with a monster that gained 400 attack and defense for each card removed from play. As it was a four-way match with rather large decks, roughly 125 monster were removed from play. All in all said monster ended up with 50,000 attack!
The Great Moth series is famous for being a bit too Magikarp. First, summon the pathetically weak Petit Moth (a caterpillar with Kuriboh-level stats), then equip it with Cocoon of Evolution, turning it into a somewhat poor Stone Wall. From then on, you need to keep the Moth protected as long as possible, so you can use it as Tribute once a certain number of turns have passed. Two turns nets you the completely useless Larvae Moth, four nets you the respectable (for its time) Great Moth, and six bestows upon you the Perfectly Ultimate Great Moth, the strongest Insect in the game by ATK. Unfortunately, the sheer difficulty of keeping any Monster alive for six turns, as well as the fact that PUGM is basically a highly vulnerable beatstick, means that the whole archetype was considered Awesome, but Impractical even when it was new, and time has not been kind to it.
In Blood Bowl, Chaos and Lizardmen teams in particular depend on this. Instead of blitzers, they start with expensive 'musclemen' units (Saurus and Chaos Warriors) who have high natural stats but no skills (especially the all-important Block), which make them weaker than other factions' blitzers (and Dwarf linemen). Once those musclemen gain one-two levels and gain access to Block and Mighty Blow, they become terrors on the field (especially if your Chaos Warriors pick up a few mutations on the side).
Chaos Pact and Underworld are two teams who depend entirely on this. Their starting players are sub-par and they suffer from expensive rerolls and high player turnover. However, their cheap players and insanely varied skill and mutation access (both have normal access to every skill in the game across their players, with Underworld having a better spread across players while Pact has incredible Marauders) means that a team of level 3+ underworld players are a Jack of All Stats team to be feared.
Da Orks are a 'n-ooniverse example! 'Ur av'rage Grot is puny and no match for 'nyone 'cept maybe one o' dem puny 'umie Guardsmen, but give 'im a few years an' he'll be a full-fledged Boy 'oo can crump a panzee 'umie easy and be a good enuff threat to a Space Marine! Give 'em even more time an' he'll grow up to be a tough Nob, an' Space Marines may be dead-'ard, but even dey leg it from dose boyz! Wot Iz tryin' ta say iz, even da runtiest of Orks can grow up to be sumfink real big and 'ard! An' oo knows, maybe someday dat lad may even become a real big Waghboss, big and mean enuff to lead 'iz own boyz! WAAAAAAGH!!!
Drift in Alien Dice was very small and generally considered useless by Lexx at level one, but when he finally leveled up he grew bigger than even Epsy (though it seems that most of his mass is fluff).