Most video games themselves are an example. Think about it - how many times have you played a game that casts you as the greatest hero of the universe, only for you to fail spectacularly on your first few plays?
Mario and Luigi. In the games themselves, not to mention most of the associated media (except for a certain live-action spinoff), despite their manner of dress and going through pipes, are they ever shown doing any actual plumbing? This was pointed out in There Will Be Brawl.
They were finally shown doing plumbing in Mario & Luigi: Superstar Saga. Granted, they were forced to do it as part of a plan by Cackletta to unlock the Beanstar from its cage
In Luigi's Mansion: Dark Moon, there is one mission called "A Job For a Plumber" that involves Luigi restoring the water system in one of the mansions. (Of course, fighting ghosts and dodging demonic crows usually isn't in a plumber's job description...)
Supposedly Isabelle of Animal Crossing is a super hard worker with no time to rest, but the only evidence for this is just taking Isabelle's word for it that she isn't lying about being busy. The player never actually sees her do any sort of paperwork or any other work, she's always either standing in place or sleeping, she doesn't contribute to the public work projects, and the only service she provides that doesn't involve just telling you information is organizing a few events, so what exactly Isabelle does as your secretary that keeps her busy every day is highly questionable.
Gordon Freeman from Half-Life is a theoretical physicist... yet the most technically advanced things he does in the series is push a cart, flip switches, and plug in equipment. Lampshaded by Barney Calhoun in Half-Life 2 when he says "Good job hitting that switch. I can see that MIT education really pays for itself."
He apparently picked up some mechanical knowledge at least, picking up any weapon and figuring out the controls quickly, even alien ones like the overwatch pulse rifle, successfully subverting Unusable Enemy Equipment.
Of comparable informed ability status is Isaac Clarke, the protagonist of Dead Space. He is said to be known for original and innovative engineering solutions, yet he never displays any knowledge of engineering through the first game.
Averted in Dead Space 2; the first things Isaac does is flaunt his engineering degree by combining a medical laser and a flashlight to make a plasma cutter, and then going about manually rewiring electronics.
Averted even further in Deadspace 3, which gives him the ability to build his own guns.
Solid Snake is supposed to have a 180 IQ, he tends to believe almost everything people tell him.
Similarly with Liquid Snake who is also supposed to be a genius, but has a grasp of genetics that would make a middle-school science student point and laugh. You might want to actually read about a subject before you build your entire life around it, Liquid.
Metal Gear RAY's ability to take down Metal Gear REX and its clones is either an informed ability, or in-universe false advertising. Raiden can take down multiple RAYs on foot with a rocket launcher in the same time it took Solid Snake to take out a single REX, then went on to throw a RAY into the air and hack it to pieces in the trailer for Metal Gear Rising: Revengeance. When REX and RAY finally square off in MGS4, REX can take it down without too much difficulty. And this is a brand-new RAYnote no, it's not the prototype stolen by Ocelot in MGS2, since it lacks the original's long tail fighting a damaged REX after the latter was blown up, left in a freezing cold warehouse for almost a decade, and then had a major structural component removed without much thought for how the rest was going to balance without it, leaving it a wonder the REX in question can even stand upright.
Godot apparently can do an excellent impression of a previous witness, but seeing as the games are text based all that happens is that his Leit Motif changes.
Godot gets to perform impressions of two witnesses. When he's impressioning a female witness, the speaking-beeps switch to the higher pitched female ones too.
Godot is constantly feared by police and other prosecutors alike for being a powerful attorney. He's the least successful prosecutor in the entire series. He never wins a case, both on-screen or off, where as Winston Payne is at least noted for being undefeated up until his trial against Mia. It's justified only so far with him being a defense attorney, but he uses tricks and plots that revoke that.
Godot's prowess as a prosecutor is brought up before you meet him: Gumshoe talks about how he's never been defeated. This turns out to be entirely true; the case where you meet him is his first one as a prosecutor.
Averted in a clever way with Lamiroir in Apollo Justice: Ace Attorney. She is considered a world-class singer, with an angelic voice. How do they put this on a DS game? They don't record vocals, and instead give her voice as a musical tone. The effect works, her voice sounds brilliant, but it isn't quite Show, Don't Tell, as it's clear each of those tones represents her voice.
Apollo Justice: Ace Attorney does play this trope straight in regards to Kristoph Gavin. He's supposedly an excellent defense attorney, but he's only shown defending in one case, and only as co-counsel at that.
And then there's the above-mentioned Winston Payne, called the Rookie Killer for his habit of crushing rookie defense attorneys. He never wins a single case on-screen (except when the defense is trying to lose,) even when his opponent has amnesia, and quickly falls to Butt Monkey status.
Your stats do have an impact on your interaction with the world outside the vault. In the tutorial in the vault, however, Butch (strength 5 out of maximum 10 according to the construction kit) will always attempt to bully, even if logic dictates that if you are stronger than him he is going to get his ass kicked if he provokes you. Neither will your charisma score affect your interactions with other vault dwellers in the slightest: even if you have 10 in Charisma, Amata will still be the only one in your age group that actually likes you, all others being hostile or indifferent. High Skills do offer some extra conversation paths however.
Protectron Robots are implied to be extremely fast and efficient factory workers, so much so that a Factory variant exists (yet still comes equipped with a built in laser pistol), however in gameplay, Protectrons are clunky, stiff, bulky, noisy, and slow. They also suffer from limited movement abilities due to their design (so tasks as simple as using a shovel are impossible). Even if they've gone without maintenance for 200 years, one can only wonder how such a machine could actually outperform a human. This is lampshaded in the epilogue of Fallout: New Vegas if you reprogram Primm Slim as the town sheriff of Primm. He's stated to be able-minded but not able-bodied with his slow speed leading to a few crooks managing to get away.
It is supposedly so hard to remove a Pipboy 3000 without the correct tools that generally the only viable method is to saw off the users arm... and yet both the Lone Wanderer and the Courier seem to have absolutely no problem doing so. This isn't even Gameplay and Story Segregation as it is possible to buy a gold Pipboy from a Freeside merchant and swap them over.
Used for a gag in Megaman Battle Network 2; when a villain is captured, he expresses disbelief at how two kids could beat him, future head of Gospel (note: ego), with an IQ of 170. Chaud informs him "Your IQ of 170 didn't help you this time."
In 3, Tora constantly mentions "strategy" and "thinking several moves ahead" and is even introduced in the N1 as a "master strategist". His navi, KingMan is one of the cheapest bosses in the entire series, its "strategy" consisting of staying in back row while a bunch of autonomous chess pieces continually harass the player.
Leon Silverberg of Suikoden II is supposed to be perhaps the greatest strategists to ever live. Except we only see brilliance from his former student Shu, who is so terrified of Leon's unbeatable brilliance that he nearly kills himself to bring Leon down. Never mind that we never see Leon do anything all that special. Considering the mind-boggling brilliance of some of the strategists in the series, Leon is an extreme case of this trope.
The wingmen you fly with in the Wing Commander games are all supposed to be truly badass veteran pilots, but with a relative few exceptions... well, they aren't.
Knight rarely seems to make it back with any kills, or indeed his fighter, even though he has an impressive service record prior to the start of the campaign. Lampshaded in the movie, where he dies spectacularly.
In Viva Pińata, it is mentioned that the Eaglair "has earned respect through its natural nobility, tempered strength, and thumping great talons." Somehow that 'respect' doesn't seem to stop larger Pinatas from walking over it, and it's 'talons' are somewhat nonexistent due to the Eaglair's legs and feet being a pair of stumps.
In Monster Rancher Battle Card Game: Episode 2, you're allowed to lose as many times as you want because you're always wagering a "Critical" card, which Cue has a massive stack of. Every NPC seems quite interested in getting this card for themselves, going so far as betting fifteen other cards or one Monster Card (...and more skill cards) against it. Critical, however, isn't that good a card— it takes two GUTS to use, and adds two points to another attack (which can still be dodged or blocked). A lot of attacks have better GUTS-to-damage ratios, so it's often better to replace Critical with... just about any other card.
A lot of Pokémon have an Informed Ability in their Pokédex entry, which we never actually see, especially not after catching them. While many Ghost-type Pokémon are able to steal souls, some Psychic-types are hyper-intelligent and empathic and able to rip apart time and space. Also, some legendaries are stated to be able to travel through time, wipe people's memories, permanently paralyze, them or even kill them by merely looking in their eyes. In the end, all that's really impressive about them are their stats in battle... if you train them properly.
Granted, Cyrus in Diamond/Pearl explains legendary Pokémon lose part of their powers when they are trapped in a Poké Ball the first time, and that's why he gives you a Master Ball free of charge and leaves to steal Dialga/Palkia's powers by himself.
Ghost-type attacks in Generation I were supposed to be super-effective against Psychic-type Pokémon but possibly due to a programming oversight, Ghost-type moves cannot hit Psychics, leaving a major hole in the Elemental Rock-Paper-Scissors formula and resulting in the Psychic type becoming a major Game Breaker until later generations fixed it. By sheer coincidence, the same is true of the anime's first season; Ash brings a Haunter to fight Sabrina's Kadabra because Ghost hurts Psychic. But the Haunter in question never uses any Ghost attacks, instead using humor to make Kadabra laugh.
In Pokémon Black and White your two rivals are the ditzy Bianca who admits she isn't very good and the analytical Cheren who is focused on nothing but becoming the champion. In your fights with them however, while Bianca isn't a particularlly hard fight, she is still harder than Cheren who has an abysmal set up for his team note His two Pokémon that differ from hers are both physical based glass cannons. Knowing this he decides that both should use sets that depend on them surviving an attack o and the second should run a set with no physical moves. While he tries to give one a set up so he will always critical, he doesn't actually complete it and deletes the move needed to pull it off by the time he has put the other pieces together.
Similarly, Blue in the first generation games is supposed to be an incredibly skilled trainer, but his team's setup by the time he's the Champion is pretty awful. His Rhydon has two moves that do the exact same thing and no Rock or Ground moves, his Alakazam has Psybeam and Psychic even though the former is just a weaker version of the latter, his Charizard has Rage, one of the worst moves in the game, his Gyarados has kept Dragon Rage long after when it would be useful, his Arcanine is still using Ember, and his Exeggutor has three moves, which is impossible by the mechanics of the game. The remakes mostly fixed this, and by the time of HeartGold/SoulSilver, he's an actual threat.
It's possible the way N speaks just can't be rendered through the largely-visual game medium, since he is supposed to be somewhat strange.
Charizard's flames, according to several Pokedex entries, can melt boulders. Except the boulders that require Strength to move. And the smaller boulders that require Rock Smash to break. And Rock-type Pokemon, which not only resist Charizard in Elemental Rock-Paper-Scissors, but deal Quad Damage to it.
Pidgeot is noted in no less than five Pokedex entries to be capable of flight at Mach 2. You'd think this would make Pidgeot one of the fastest Pokemon ever, but until Gen VI, its base Speed was 91, which is more or less just above average - in fact, it's the second slowest fully-evolved regional bird, outstripped by Swellow, Staraptor, Dodrio, Unfezant, and plenty of others. Gen VI eventually took pity on the thing and gave it a speed boost to 101 (which is actually respectable), and a Mega Evolution that boosted it further to something that actually would approximate Mach 2.
Though Escavalier's entry doesn't say it breaks the sound barrier, it does describe it as flying at high speed. Given that Escavalier's Speed is 20 (tied with Ferrothorn for the lowest of any final-stage Pokemon, and significantly behind such lightning-quick luminaries as Snorlax and Slowbro), many fans wonder what metric under which Escavalier could be described as high-speed.
Averted in Boktai. Master Otenko is the representation of The Sun, and a guardian of the Solar System... but he makes it clear to Django in the first game that he can't fight. Indeed, Otenko does get his leafy stem handed to him on a regular basis.
In Soul Calibur IV, Angol Fear, the "King of Terror" is said to weigh 1.44 tons, and be 14800 years old. Given that, you would think that she would be super strong, unjugglable, and more of a threat than all of the fighters in the game considering the knowledge she should have amassed. The character is Seon Mina. Not Shin Seong Mina or Seong Mina with a speed boost or a health boost or extra combos or power armor or juggle resistance or any discernible advantage whatsoever. It's just Seong Mina. Actually a little worse, because her weapon is slightly shorter than Seong Mina's, meaning that in a scant few cases, she doesn't have the range that Mina has.
In Lunar: The Silver Star, Luna is loved by her entire village for her singing voice. Unfortunately, they gave her a voice actress who doesn't measure up to the apparent reverence and occasionally hits a sour note.
Touhou characters possess a vast array of magical abilities, ranging from control of insects to being an intense luck charm to manipulation of wind to absolute mastery of borders, however as the genre of the games is Bullet Hell those abilities rarely appear in gameplay, which a few exceptions (like Utsuho throwing miniature suns at the player, Cirno throwing Icicles or Mystia making the player's field of vision reduced in Inperishable Night). This is given an in-story explanation with the implementation of the spell card rules, both providing the weaker denizens of Gensokyo a reasonable chance of success and preventing the stronger denizens from simply vaporising their opponents.
However, in the fighting games their abilities are shown much more clearly (Sakuya's time manipulation, Meiling's martial art, Youmu swordfighting, Komachi's manipulation of distances etc...), excluding of course some exception like Yuyuko being able to kill anything, or Remilia's manipulation of fate.
In BlazBlue, Iron Tager is supposedly around 550 kg, as Teach me, Ms. Litchi! tells us, but you wouldn't know that from the way everyone else lighter than him can still toss him around. Admittedly, it would be unbalanced to make him immovable to others' attacks.
Several of the characters are apparently capable of impressive feats, but even Gameplay and Story Segregation aside, we never get to see these powers without the character in question having outside help.
In fact, when given the chance to prove it, more often than not they are found wanting.
Dunkoro in Guild Wars is supposed to be a good planner, but doesn't actually get to show this much in game. (Partly because a lot of the story consists of reacting to things, though when Dunkoro does give advice, it is often quite basic.)
For those unfamiliar with the books, a number of NPCs from The Lord of the Rings Online can be seen like this. One of the most jarring examples is Samwise Gamgee: The Guardian class (a tank class who is described as protectors of those in need) is partly based on him and how protective he was of Frodo in the books, and higher-level players are sent to Sam as part of their training. Imagine the surprise when learning that the "guardian of unmatched skill" is a nervous hobbit who says things like "We are in quite a pickle, aren't we, Samwise old boy?" It's even more noticeable if you're playing as a hobbit yourself, who by then should have a good number of heroic deeds behind them.
To quote an LP of the Chzo Mythos: "In case you haven't noticed, John is even worse at psychiatry than Trilby is at stealing. There is not a single instance in the entire series of a protagonist actually demonstrating a skill we're supposed to believe they have." Note that this is referring to the Chzo Mythos series, which doesn't include Trilby: The Art of Theft.
In Starcraft II, General Warfield is supposed to be this badass general, and yet his entire career over the course of the game involves him screwing up the attack on Char and handing over command to Raynor, who lampshades it prior to touchdown.
You can't plan for the zerg, general. They won't fit into your nice, clean timetable.
In Sam & Max Hit the Road, Conroy Bumpus is supposed to be an incredibly highly-rated country-western singer. When we hear him sing his Villain Song, his voice is clearly a pretty good attempt at singing, but pretty shaky. Lampshaded in that Max calls Bumpus's singing 'atonal warbling',
Also, a lot is discussed about Trixie's singing, yet we never actually hear her sing even once in the game. Particularly noticeable since she's part of Conroy's backing band, yet plays tambourine instead of the song's female backing vocals.
Sam & Max Save The World, Sam's singing/banjo playing is supposed to be horrible, to the point where in a later game, Girl Stinky claims Poison Control insists she has a CD of him singing to use as an emetic. Other than a bit of contrived Hollywood Tone-Deaf doggish howling, his singing voice is actually pretty good.
Welkin, who the game tells us is a genius. Mostly, he's just Lieutenant Obvious who happens to pay more attention to the environment because he's a biology geek. The one time he's ever seriously pressed for a solution to a crisis, he flubs it. When the problem is solved by means he doesn't like, he can't argue with the logic behind it or come up with a better solution, so he just socks Faldio in the face. Further, Isara's death occurs when Welkin apparently thought it was cool to have the army camp out in an open field for tank repairs without cover, or even posting watch, and Alicia attempts suicide because Welkin gave her the brush-off when she came to him, in tears, for support.
Garland from Final Fantasy I is supposed to be a great warrior that no force in Corneria was able to stop once he turned to evil. His reputation for being quite easy to beat by the Light Warriors has become legendary (as well as creating the second-greatest meme in the franchise's history). Only on the surface, anyway, as he does turn out to be the Big Bad. With the power of Time Travel, he actually arranges his own rescue, ensuring he can be set up to go all A God Am I later on, while still summoning the Fiends to wreak havoc.
In the original game, he is constantly regarded as being a "Tactical Genius", even from Major NPCs like Cairne Bloodhoof and Thrall, and even from the Blizzard Team themselves, but anyone who actually did the quests and events that involves him would know right off the bat that he is lightyears from being remotely regarded as this:
The Burning Crusade introduces Garrosh, who at the time was sooo wangsty about his father's legacy and the deteriorating health of the Greatmother, he never lifted a finger to help with the numerous issues plaguing his clan the Mag'har. You, the player character, end up covering his ass so much that upon the climax of the storyline, he was even willing to turn over leadership of the entire Mag'har clan to you so he can go die in a corner because he realized how much of a loser he was in comparison to you.
Fast forward one expansion, Wrath of the Lich King, Garrosh does a complete 180 turn of his personality, so instead of the mopey crybaby, his trademark Jerk Ass persona comes in. And during the early questlines of one of the first Northrend zones Horde players will enter, players witness firsthand that Garrosh is as impatient and reckless as his father (one of the reason he was so depressed in the previous expansion by the way), and was more interested in eliminating the Alliance forces on the opposite side of the zone than dealing with the numerous issues just outside his fortress. Later, when scout requested reinforcements to take out a Necromancer and his small army, Garrosh scoffs and sends ''only'' the player, who would have been promptly captured and zombified had resident Badass Saurfang not seen the stupidity himself and personally came to the rescue. Garrosh also had some followers in later zones who were as stupid and jerkass as he is, one of them even got herself killed by the player because of her own zeal and stupidity. Saurfang even called Garrosh out on the fact he was trying to fight a war without bother to gather supplies first. Supplies like artillery, armor, and provisions Garrosh in fact, regularly made claims along the lines of, "A true warrior doesn't need supplies, allies, or strategy to win."
In Cataclysm, Garrosh has grown up and is THE leader of the Horde. Naturally, this proved disastrous. He immediately breaks treaties and wages open war on the Alliance against the other leader's advice (effectively undoing EVERYTHING Thrall spent years trying to avoid), alienates three of the four other Horde leaders and their people from Orgrimmar, and his stupidity and hotheadedness results in getting the fourth leader killed in a duel. This is well after he was told by Thrall to LISTEN to his advisers.
There's also the Stonetalon incident, in which Krom'Gar, a corrupt general of his, burns down half the zone and blows up the other half. Which result in Garrosh "dismissing" Krom'Gar after giving him a lecture on honor. Which some of his few fans would consider both a Crowning Moment of Awesome and a Pet the Dog moment - Until you realize that Garrosh was the one who put Krom'gar in charge of that expedition in the first place, (and failed to check on him until it was far too late), and thus is the one ultimately responsible for the whole mess.
In the Twilight Highland quests, you witness an epic display of his monumental incompetence from the get-go: In his usual impatience, he orders his goblin engineers to build a fleet of zeppelins to protect his supply carriers from the Black Dragonflight with little time or resource to actually complete them. When the ships are deployed, they can't even stay in flight, and one of them actually crashes. And then Garrosh spots an Alliance navy fleet and immediately orders his attacking ship to make a beeline for them, which would leave all the remaining supply and transport ship completely undefended, a Goblin Captain even questions who'd be stupid enough to do this, but gets punched by one of Garrosh's loyalists for protesting - who remarks that a "Winner" would do so. The Horde fleet attacks and defeats the alliance, however this leaves the carriers completely helpless, as expected the Twilight Dragonflight shows up shortly after and takes out just about every single carrier. Leaving Garrosh, the player, and a few survivors to be washed on shore after. And when you talk to one of the other survivors, apparently Garrosh, in an attempt to save face, claims the alliance attacked them unprovoked.
Aside from his lackluster command abilities, he's also supposed to be a great warrior. Now, he's probably pretty good in his own right, but so is just about every other noteworthy character in Warcraft, and when he's up against other lore figures he tends to do poorly. He was beating Thrall in their duel in the Wrath of the Lich King pre-event, but this was later explained as Thrall holding back to avoid humiliating him. He only won his Mak'gora with Cairne because Magatha Grimtotem poisoned his axe without his knowledge. And Varian had him beat in Wolfheart, were it not for his troops pulling him off the battlefield while Varian was distracted he likely would have been killed or taken prisoner. In fact, Garrosh has never won a fight with another major character with his skill alone. Garrosh himself may be becoming increasingly aware of this, as in patch 5.1 he attempts to have Vol'jin assassinated, rather than killing him outright.
Garrosh gets a proper in game cinematic fight with Thrall in Warlords of Draenor. Thrall is on the defensive the whole time, but once the talking is over he brings out his shaman spells. It ends very quickly at that point.
Sylvanas Windrunner. Seeing how she is implied to be super threatening and intelligent despite her tendency of keeping potential traitors close to her AND having the "super brilliant" strategy of bombing everything with plague. She also gets her rotting ass handed to her on several occasions by other major characters - often having to resort in her underhanded tactics in the first place. She also gets killed by a single bullet through the chest by one of the said "potential traitors" just after ransoming another NPC.
In Kingdom Hearts, Luxord of Organization XIII is stated to have time-based powers, which extends to putting a "Time Limit" in his boss battle that really just ends up being "Hit Luxord a lot" and fights more with his cards.
In Fate/stay night, Gilgamesh, the Big Bad of one route and The Dragon of another apparently has such a high charisma (A+ rank) that his goes beyond "Can be said to have achieved the greatest level of popularity as a human being" (which is A rank). However, you never, never see him doing anything remotely charismatic. Quite the opposite, actually. He spends his whole time being a Jerk Ass, Smug Snake, Social Darwinist who tries to rapeSaber.
Judging by his reputation, Amoral Attorney Igland of the Swift Sword in Neverwinter Nights is a very talented lawyer. Judging by his actual performance in the game, if this is true it is a dire statement on Neverwinter's legal system, since Igland's idea of a compelling case in a murder trial is "the defendant is a dirty savage and therefore we should hang him". One wonders how much of his reputation for having never lost a case involved passing Exhibit M, a large sack of money, to each juror.
Sonic's speed is sometimes this relative to the other main characters, especially in the older games before the characters' abilities had speciated as much. For instance, some of the earlier games contain situations where Knuckles, Tails, and even Robotnik can run as fast as Sonic. Tails can still fly as fast as Sonic runs, but they make sure it looks like he's flying. Not running. They also state that Sonic can run faster than the speed of sound. This seems to be an exaggeration. Even though he moves unbelievably fast, he never actually comes close to breaking the sound barrier.
Tales of the Abyss, Van is stated to have taught Tear the Fonic Hyms, but in actual battles he only uses the fifth, and even then he doesn't sing it. Though is implied to have used them off-screen after his first defeat.
Nanaly's skills with Archery is said to put 1,000 men to shame. However, in Gameplay, the battle system works against her massively, as arrows are both slower than melee (and thus can't do damage as quickly) and do less damage than magical attacks, and she is frequently placed on the bench the second a fifth party member is available - because the game gives her the shaft. However, in other games where she cameos, her archery abilities don't get the shaft at all.
In God of War, Kratos was stated to have a large amount of success as a general in the Spartan army, which would be more passable if not for the fact the sequels depict as being Too Dumb to Live.
Most commander characters in Command & Conquer have bios stating how smart they are, but fail live up in the game's plot, apart from Slavik and Mc Niel in Tiberian Sun, but only because they're the player characters.
In Final Fantasy X, Tidus is a famous blitzball player, which implies some degree of skill, but in the actual blitzball minigame he starts out fairly mediocre - at the start he's the best shooter on the team, sure, but that team is the Besaid Aurochs, who start out with the overall blitzball competence of a spoon.
Vagrant Story has Lady Samantha and Callo Merlose. Samantha is a Catholic-schoolgirl-styled, doe-eyed ingenue who we're told is a captain of the Crimson Blades; Callo Merlose is a VKP Inquisitor who spends the entire game as a hostage who is supposedly capable of defending herself (but chooses not to, because she's a psychic spy and her captors were the ones she was supposed to be investigating). Either way, we don't get to see them do much of the stuff they're supposedly able to do.
Merlose gets something of a pass on this one; she's armed with a buckler, but no weapons, because she's an investigator and not a soldier, but once she manifests her psychic powers there's not a lot of point in trying to use the conventional interrogation tactics she's supposedly good at. Samantha's incompetence is a plot point: Guildenstern needed a pure soul to sacrifice, and it's implied that he gave her the position to get her into the city and keep her close.
In Final Fantasy IV, Cecil, the main character, is described as a Dark Knight who later goes on a mission of atonement to repent for his "blood-drenched past". However, from the very first time you play him, he comes across as considerate, merciful, optimistic, naive, etc. It's not exactly a believable Heel/Face turn when you start out as a Face to begin with. The first few minutes of the game see him overseeing the slaughter of innocent villagers. Sure he hates every second of it, but from the get-go we're presented with at least one thing he could realistically wish to atone for. Since Cecil was never presented as evil in the first place, it was not a case of heel/face turn, and more a case of him finally standing up for himself. As for why he's a dark knight, the lore of the series (the main game, its sequel, and Dissidia) clearly paint this as a case of Dark Is Not Evil.
The universe of Final Fantasy XIII (Specifically, Final Fantasy XIII-2) brings us Caius of the Ballads. Promoted as one of the most sinister villains of the entire franchise. You wouldn't know it by how easily you kick his ass during boss battles. Honestly, even though his battles end when he uses auto-life, you'd probably take down that second bar with no trouble.
At the beginning of Golden Sun, Kraden mentions that carrying just one of the Elemental Stars could give you enough power to rule the world. The player character for the first two games has one in his inventory, and all it does is take up space. Justified in that all concerning the Elemental Stars is speculative legend, since they've been sealed away for countless generations as of the first game (and that our heroes don't want to rule the world).
Also, the Feelies for The Lost Age mention that Sheba has the power of precognition. The only time this comes up in-game is when Sheba insists it's her destiny to accompany Felix on his journey... and she later admits she was lying about that.
A cutscene in the first game has Hama state that Ivan also has the power of prediction... to which Ivan himself replies that if he does, it's news to him.
Used to subtle effect in Borderlands 2 with Wilhelm, Handsome Jack's Dragon, a massive cyborg warrior so powerful he supposedly defeated the previous set of Vault Hunters from the first Borderlands game. When you fight him, he turns out to be a pushover and you easily defeat him. All part of Jack's plan, because by defeating the supposed ultimate minion and looting his corpse, you get a certain power core that lets Jack shut down the shields for your base and leave it vulnerable to orbital bombardment. Also, a cut piece of dialog from Jack states that he had Wilhelm poisoned prior to the fight.
In both Metroid: Other M and Metroid Fusion, Adam Malkovich, Samus' former CO, is referred to as a tactical genius with a perfect military mind. When we meet him in Other M, however, not only does he seem oblivious to things going on around him, but he makes several questionable decisions, and ultimately loses everyone in his squad except for Anthony.
Hawke in the Advance Wars series is repeatedly praised for how powerful and unstoppable he is, when in reality he's a middle-tier commander at best who boasts a pitiful 10% power boost in exchange for the slowest charging power in the game. Ironically, the Insufferable Genius / Perky Goth Lash, even after being nerfed for Dual Strike, has a FAR superior power (Her attack raises along with her defense depending on the terrain, making her unstoppable on mountains and cities) yet is seen as nothing more than an annoyance by the good and bad guys alike.
Shantotto is depicted as incredibly powerful magic user, with even her enemies showing her great respect or outright admitting she is more powerful than them. However, in the game she is so weak as to render the character nearly unplayable.
Dragon Age: Origins: Supposedly Anora is a forceful presence and would be the savvier queen but she has already been the Queen for five years. She couldn't dissuade her husband from his campaign at Ostagar even though her and her father believed it to be ill-advised and she couldn't stop Loghain from going down the path he walked as regent. Alistair at least stood up to Loghain and will (if chosen) take him down in a duel.
So Drake from Drake Of The 99 Dragons is the best and deadliest assassin in the world...Yet his main strategy involves running into rooms shooting everything in sight, pulling two more guns out of his jacket instead of reloading his previous guns which is probably the best way to have the cops on your trail, and running after the badguys head on without any sort of disguise. He also dies 5 times in the story, one of which had him jump out of a window because he thought he was invincible.
In Mass Effect 3, Thanix Cannons have supposedly been distributed across numerous fleets, giving the ships a vastly improved firepower. However, in the space battles, none of the shots fired by the other ships have the visual representation that the Normandy had when it used its Thanix Cannon in Mass Effect 2. BioWare came right out and stated that when the visuals and codex conflict, as here, the codex wins. note This may be due to a Retcon between the two games, where the Thanix's Codex entry in 3 clarifies that the projectile it fires hardens into a solid projectile before firing, which would result in something more in line with what is seen in the third game with short "bolts" of blue instead of the singe long blue beam fired by the Normandy in 2.
Celestia Ludenberg from Danganronpa is allegedly a "Super High School Level Gambler", with tons of notorious gambling-related exploits under her belt. However, when she ends up as the killer in Day 3, she's only slightly better at bluffing than the previous two killers, makes a couple of key slip-ups, and loses her composure faster than one would expect from someone with her skills. Then again, it's hard to tell how many of her claims about her skills and experience are actually the truth (for instance, the past exploits she mentions in her Free Time segments are all plots from gambling mangas).
SoulNomadAndTheWorldEaters brings us Thuris. He's supposed to be the smartest of the three world eaters, and while he IS pretty clever (creating a cult out of the fact that no one can see him and creating a dreaded disease), he's outsmarted by everyone. This wouldn't be a big deal (since these tend to be people more powerful than him and knowing more than he does anyways), if one of the people outsmarting didn't include one of the other supposedly not as smart world eaters.
Ryu lays waste to the forces of darkness on an almost regular basis, whereas Hayate hasn't so much as won a single tournament. Even his sisters have more accomplishments under their belts than he does. The most he's done, is take out a blimp during a cutscene and mow dow a small group of mooks.
Final Fantasy XII: Balthier and Fran are introduced with guns and bows respectively, and are shown with those weapons in promotional material, as if to say "these guys should be your ranged specialists". In fact, not only do they not get any bonuses using these weapons, the special animations they use make them marginally slower than everyone else, making them the worst to wield their preferred weapons! Fran is also discussed as if she's mystically quite powerful, with doors being described as having too strong a magical lock for her to break through, but she's one of the weaker mages in the party.
Call of Duty: Ghosts: The titular Ghosts themselves have this in spades. They are hyped as this ultra-legendary unit of special elite among the elite special force commandos capable of taking out entire armies with such silence and stealth, that nobody even knows they're there. In the actual game, they're notoriously noisy. Their first mission has them ramming a truck set on fire, on a stadium full of enemy forces, guns blazing. Not very subtle. In fact, most of what little sneaking around there is in this game happens before meeting the actual Ghosts.