To start with: pretty much any time a fighting game allows usage of the resident SNK Boss without significantly nerfing the playable version. And sometimes even then.
MUGEN Cheap characters. Not surprising since MUGEN contains characters from almost all fighting games. However, since every MUGENite's opinion of "broken" varies, even the most balanced of characters can be considered Game Breakers in their eyes...
There's also the A-Bomb, which is... an A-Bomb. Its only attack is creating a fullscreen nuclear explosion that can't be blocked and vaporizes the enemy. If it attacks, it uses this. If it lands from a jump, it uses this. If the opponent does anything to it, it takes no damage and uses... you get the point. Able to kill all the above mentioned characters.
Chuck Norris is in this game. True to Chuck Norris Facts, he has no hitbox, and can kill all of the above overpowered characters in a matter of seconds.
Examples would be: Oni-Miko-Zero, Debugger and Crazy Catastrophe, who are made to destroy regular characters and characters with no hitbox.
Let's just say Mugen as a whole and be done with it.
In Tekken, the use of Eddy, Yoshimitsu (and Christie in newer games) is often bemoaned by opponents and audience as the repetitive and fluid nature of their attacks leaves little room for counter-attacking.
In higher levels of play these issues disappear, only to be replaced by certain other broken elements. The most prominent example of a broken character was Jin in T4. While every Tekken has had tiers (even the most balanced game to date, Dark Resurrection), the main problem was that Jin's Laser Scraper move timed in a certain manner, in addition to his various ways of keeping pressure through frame advantage (he would recover faster than the opponent in various situations that were easy to bring about) caused him to be head and shoulders above the rest of the cast. Other than perhaps the console-only Jinpachi in DR (and even this is debatable), there has never been another character to be the sole occupant of the top tier level.
Jin's grandfather Heihachi was pretty ridiculous in Tekken 5 though. Most of the time, Tekken operates on a punishment system where moves that net low reward allow retaliation that also nets low reward if blocked or dodged. However, one of Heihachi's jab combos was fast enough to punish an opponent's low reward move with damage equal to most character's main juggle combos, when most character's jab combos did a fraction of the damage. Simply put, if a character could normally get a 15 to 20-damage point combo (comparatively low reward) in retaliation, Heihachi could get a 66-damage point combo (out of 144.5 total health on a Tekken character's lifebar). What made it worse was that the combo was three moves long. See 1:09 of this video.
Law's backflips are a spamwhich because he always does two in a row of higher difficullty levels. Law also has plenty of moves which launch you up in the air, just so he can string some backflips and juggle you.
Eddy is a Button Masher character. The ease of creating constant dancing combos means that a blind five-year-old could easily beat you if you don't know exactly how to avoid the flailing legs. Even his Idle Animation makes it hard to hit him.
For Gon, by holding + (), you can unleash a killer move that almost kills your opponent. Because Gon is small and fire-proof, he is especially dangerous.
The usage of Bob in Tekken 6 is extremely frowned upon. He is so far above everyone else with his fast, god-priority attacks that he is the sole member of S-tier in the game.
As of Tag 2, there is no top tier. There is only "Mishima Tier", because every single Mishima (Kazuya, Heihachi, and Devil Jin, in that order) dominate the top tiers due to their insane juggles, tag combos, and damage output. Jinpachi, despite his original status as an SNK Boss, has been completely rebalanced and is not considered a Game Breaker because he is not a "traditional" Mishima (he does not possess his successors' wavedashes and has a different variation of the Electric Wind God Fist).
The use of Akuma in Super Street Fighter II Turbo tournaments is banned, thanks to his ridiculous damage and combos he has in that game. Subsequent games he appeared in have Nerfed him to the point of being a Glass Cannon, and he has now become a balanced character whose presence is welcomed quite emphatically at Street Fighter IV tournaments.
In the Super Street Fighter II Turbo HD Remix, he was toned down so that he could be another playable character, but the end result of these changes was that he ended up gaining several overpowered juggles, as well as an unblockable air fireball trap which can lead to a loop. Yes, he turned out even more broken than he already was. Thus, Akuma remains banned.
Old Sagat (O. Sagat) in SSF2T (the Super Street Fighter II version of Sagat who can be unlocked in Super Turbo) is an example that sits on the edge. He's not outright banned (meaning you won't be stopped from picking him) but is still a potential game breaker. Much like the Jin Kazama example above, O. Sagat's outrageous projectile recovery enables him to lock his enemies down with ease. Because of this, and in the interest of tournament diversity, he's "soft banned" in Japanese events (meaning that the players collectively agree to not pick him) as otherwise, the game would be so heavily skewed towards his usage and would likely monopolize the character selections for all participants.
In Street Fighter IV, did you want to tackle all of the AI challenges without ever breaking a sweat? Zangief. Double Lariat. Repeat et nausium. You're welcome.
Guilty Gear tournaments traditionally ban the characters Kliff, Justice, and (depending on the version of the character) Robo-Ky.
This is not because they are game breakers per se, but because they were added in console versions as bonus characters without taking the time to balance them with the rest of the cast. Exactly how broken or not-broken they are is debatable, but the community, not wanting to take any chances, chose to pre-emptively ban them. The same principle applies to the EX characters, alternative versions of regular characters that are gradually unlocked in the console versions.
The tier list for Guilty Gear XX #Reload is usually defined in this fashion: Low, Mid, High, and Eddie Tier. Yes, Eddie completely dominates the entire cast with his godlike unblockable setups with his shadow attacks, as well as the ability to dizzy any character in just 2-3 combos.
In Accent Core Plus, Eddie reclaims his top-tier spot, but now shares it with Testament and Slayer.
Duo Lon was once banned in The King of Fighters tournaments, until he got his infinite combo taken away in KOF XI.
Also, Choi. Virtually all viable options, setups and combos are rendered obsolete because of his size.
In '98, we have Goro Daimon and Iori Yagami. Goro has a variety of odd glitches that make him an absolute monster, and Iori capable of just about any type of play style you can imagine. Not to mention Iori has had the same infinite in almost every one of his appearances.
Said "Goro infinite" bug was removed in Ultimate Match, placing Goro back into a more complacent spot on the tier list. However, Iori was practically unchanged, and he had Geese and Krauser join him in the top tier. Expect to see teams consisting of these three a lot.
Ralf Jones from The King of Fighters EX2: Howling Blood on the Game Boy Advance. Remember his Galactica Phantom HSDM from the main series? The horrifically lethal, yet easy-to-dodge charge punch? Well, he has it as a normal move in this game. It does less damage—only 50% of a lifebar—but it has a much much shorter charge time, meaning you can actually use it and connect most of the time, it gained some anti-air priority AND it's still unblockable/puts Ralf into autoguard mode for its duration. Needless to say, spamming that move makes playing as Ralf fall somewhere between Easy Mode and outright cheating. It actually makes fighting the final boss somewhat even, which is saying it all.
Ralf had that as a normal move in the main series as well.
Ralf was originally given Galactica Phantom as a normal DM in The King of Fighters '97—it was Awesome, but Impractical because your opponent would have to be an idiot to be hit by it. However in KOF '98 it became broken because of a highly obscure combo: Ralf could cancel one of his his OTHER DMs (his Blazing Vulcan Punch, which is much easier to connect with) into Galactica Phantom just before the last hit. This would result in the opponent being knocked to the ground while Ralf charged up, causing them to automatically stand up JUST in time to be hit by the (unblockable) Galactica Phantom. It was all but an instant kill on any character (except Choi, who was short enough that the move would go over his head if he ducked).
Raiden in KOF XIII. His dropkick combos pretty much kill any other character. And they destroy 75% of your guard meter ON BLOCK!
This is being rectified in the home versions, which will update the game to version 1.1 and rebalance everyone. One of the confirmed changes being that Raiden's dropkicks now have a much longer charge time, making all of his overpowered setups and combos impossible.
Soulcalibur III has several moves that cannot be easily parried or blocked by the game's AI (different from the designated unblockable attacks, which are too slow to put to any real use). Hardcore gamers consider them cheating, but considering a CPU opponent in this game can actually block front attacks while his/her back is turned, many players have no qualms whatsoever about cheating back.
Soulcalibur's Nightmare had a two-hit strong, strong default combo. If the first hit missed but the second hit, the result had quite a tendency to instantly catapult your opponent off the stage. Then there was Maxi, who, while you couldn't do much against the cheating AI with him, allowed most unskilled players to demolish more or less any human opponent just by pressing buttons at random and fiddling with the joypad. No wonder he stayed dead.
Talim's back-A move first strikes high, then low, and if it hits, the opponent gets knocked down. It's quite easy to force the opponent to the edge of the arena, use the move, and knock him off.
Some weapons in Soulcalibur II, believe it or not. Back then, use of certain weapons had special effects tacked onto them, such as increased damage, range, and even speed.
Most notably, Mitsurugi's Damascus Sword and Yun-seong's Han Guang, both of which had extremely long range, longer than even Kilik's staffs.
Ivy was pretty close to game-breaking when used by a competent player in Soulcalibur II. She had the longest range in the game, sweeping attacks to hit sidesteppers, and excellent knockback / blockstun to keep opponents at a range where they were useless. She also had a fast, mid-hitting ringout kick (back+ K) for when an opponent's back was to the edge, a ringout THROW when her back was to the edge, and ANOTHER powerful ringout kick (fwd,fwd+ K) if the ring edge was to her left.
Hilde in Soulcalibur IV has a string that almost always guarantees a ring out, while not broken per se, the general annoyance of fans at the move is such that players who were doing it were loudly booed in Evo 2009. Nowadays, she's banned from tournaments. Fortunately, in Soulcalibur V they wised up and removed the combo entirely.
A balance patch, however, has given her an infinite...which simply involves using her charged B attack, then charging up again for the level 2 version, and once the opponent is overhead quickly turn around and use the attack again. Fortunately, the use of this infinite has been banned until such a time where Namco can patch the game once more.
One of Link's basic throws in the GameCube version of SCII. For games versus actual people, not terribly useful, but for the Weapon Master mode, a complete gamebreaker, since most games in that mode can be won by ringouts, which are easily accomplished using this move, since you can ringout your opponent with your back to the stage edge.
Yun-seong. Fast kicks, heavy sword attacks, long combos, and the most annoying piece is one of his most basic attacks that is endlessly chainable and attacks in a high-then-low pattern. Unless you've learned how to parry and know when to use which height, it can get really annoying. But considering he is mid-tier.
Xianghua has any number of move that can be easily abused, but in the third game her guard-breaking spin move has her go in low and fast with a guard break move that has basically no recovery time AND the move had tracking, so your opponent can't side-step the move at all. On top of that the lack of recovery time allows you to get a second hit in that will knock down your opponent and then you can follow up with another one that will hit them on the ground. and even after that you can follow up again as your opponent gets up and hit them since the move covers a decent amount of distance and has tracking, an opponent trying to get back up has little to no chance of dodging it.
Nightmare in V had this status. It is fairly easy to ring people out with him, and once he gains momentum there are only a few ways of putting a stop to his extreme rushdown tactics. However, he is no longer considered this...
...But someone has taken his place. Enter Viola. Just when you thought her tactics were annoying enough already, renowned fighting game renaissance man Tokido claimed at an MLG tournament that he had "hidden technology" to show at EVO that he believed would force Namco to patch the game. That "technology" was an extremely stupid and broken infinite involving Viola's back throw. With careful inputs, Viola can use her back throw to constantly reposition her opponent towards the edge of the ring, or simply keep doing it over and over until the opponent just gives up. The use of this infinite is now banned.
Naruto: Gekitou Ninja Taisen! 4 generally bans the use of Akamaru (the dog) since most characters have an extremely hard time hitting him, due to his small size.
Akamaru isn't the only one. One-Tailed Naruto, Cursed Seal Lv. 2 Sasuke, and Itachi were HUGE Game Breakers. OT Naruto has a grab attack that stretches and catches the opponent from across the stage. Itachi could send out Clones that attacked from a distance and could teleport. Some fans complained they'd "Nerfed" Itachi, among with several others in the Sequels.
There's Sasuke in the Shippuden games, where he has an easily spammable attack that can be repeated nearly infinitely.
Bando can be considered one, incredibly fast, powerful attack, long range attacks which can stun opponents easily, as well as the fact that he can use a special that prevents flinching, he takes damage, but that problem is taken away in that he can land hits on you while you're attacking.
As of the third Shippuden, the Power Levels have gotten to the point that every character except Neji and Shikimaru has at least one move that would be considered a Game Breaker in a normal game—it's a bit like if Brawl Minus were a serious project. Even among this elite, however, the three characters who have invulnerable allies in combat (Kiba with his dog, Kankuro with his puppets, and Chiyo with her (different) puppets) are considered overpowered compared to the rest. And Kankuro's puppets are overpowered even for the trio, since even while he's hitstunned they can attack his opponent from behind with a hard-to-dodge special attack that takes off half the target's health bar.
Tenten goes here as well. The girl has a SLEW of weaponry from things that automatically destroy shields, to somethings that reflect attacks, to a chain attack that hurls you, to More Dakka, to a weapon that makes you duck. This is able to dodge some attacks in the game. Tsunade is also noted as one of the more powerful characters with insane strength, combos, and healing. Kagura has a bunch of chains and long range attacks that will definately get up in your face - beautifully noted when she can fly across the stage with just two presses of a button. Towa has a drill that will break your shield after a hit. Asuma is INSANELY powerful. And Kurenai has olbique attacks that leave you absolutely defenseless and stunned. Though, Kurenai isn't as much of a gamebreaker here as she is in the PS2 games where she's regarded as Nigh Invulnerable. Also of special metion goes Temari, who has wind that can entirely rip you apart. And let's not even get started on Baki with his game breaking slicing wind, or Yugao with her insane speed. The games are more of a World of Badass than the Manga!
Tenten's is negated by the fact that her moves are generally hard to learn, though, and impractical.
Mortal Kombat Trilogy had Noob Saibot with a terribly powerful infinite combo which involved his disabler projectile that prevented the target from making hostile contact with Noob, allowing the player to thrash away with his pop-up combo, his insanely easy and abuse-happy kick combo and sending out hyper-fast clones that lift the opponent in the air. Not to mention his Teleport Grab.
All you had to do with Noob Saibot is use his No-Block ball to prevent your opponent from blocking, then press low kick, low kick, low kick, low kick. Seriously, it's that easy. You could execute this combo twice before the effect of the No-Block ball wore off, making most fights a joke. This combo even ownedShao Kahn, and pretty every other fighter except Motaro because he was immune to projectiles.
Even then, Motaro's weakness was combos... yeah.
When using Quan Chi in Mortal Kombat: Deadly Alliance you use the "grab" move, in which Quan Chi jumps on the opponent's chest and bashes them several times in the face. After this, they fall to the ground. Time the next grab move right and you can repeat this until the opponent sinks to the ground unconscious, since there's a brief moment while standing up in which it's almost impossible to block.
Speaking of Deadly Alliance, Frost. Ground Freeze. Uppercut to Ground Freeze. Uppercut to Ground Freeze. AGH!
Mortal Kombat 2 and Kitana's ever-infamous Fan Lift. Notice how nearly all infinite comobs at least require a series of precise attacks in quick succession? Here's Kitana's: Retreat to corner. Jump over enemy, crossup jumpkick. Fan Lift. Advance a bit. Then casually mash high punch while the hapless foe is juggled into oblivion with no way out. (This absolutely owned Kintaro and Shao Kahn, to put it in perspective.) It was so stupid, in the update, Midway limited Kitana to one punch after a Fan Lift, the only time in my memory they had to put a lid on a basic attack.
The arcade version of Mortal Kombat 3 gave us Nightwolf, who could run faster than someone being thrown. Throwing is unblockable. Yeah.
Throws have ALWAYS been blockable, hold Back & Block, you'll take chip damage, but it's better than a throw.
Not to mention he had one of the quickest projectiles with virtually no lag time afterwards, and he could reflect other character's projectiles back at them.
Kabal. Good God, Kabal. He's so fast that he could probably beat up everyone in the Black Dragon AND the Red Dragon on his own with only a Run button as a weapon. Nightwolf's throw combos got nerfed early in vanilla Mortal Kombat 3's life cycle, but Kabal kept running circles around everyone else all the way to Trilogy.
That Super Speed actually defines Kabal, which is probably why he doesn't receive nearly as much hate as MK 3's other infamous game breakers.
Nightwolf, considering that he has one of the fastest projectiles in the game with virtually no lag time, has the ability to reflect his opponents projectiles, and has solid combos that do decent damage as well.
Stryker has to top the list for biggest game breaker in Ultimate Mortal Kombat 3. Why? Because that was when Midway decided he needed More Dakka. Once that got introduced, all someone playing as Stryker had to do was stand far away from his opponent and go back, forward, high punch until the opponent died. No wonder he was a Creator's Pet.
Stryker was always combo happy even before he obtained the use of his gun. One popular chain for those who actually played him was to pop the opponent into the air with a HP, HP, LP combo and then use the Nightstick Flash (F, F+HK) move while the enemy was airborne to toss them to the other side of the screen. Then while you are trying to get to your feet the Stryker could Nightstick Flash again to get close and repeat the whole process. If the Stryker was more forgiving then they could just lob a grenade in your face.
In the original Mortal Kombat, if Sonya managed to land a Leg Grab, she could repeat this move infinitely until her opponent's health ran out. To make things worse, the grab was unblockable.
You want to talk about cheap in Bleach DS? In the Japanese version of the first game Kenpachi Zaraki has a special that makes him invincible for its duration and teleports him in front of the opponent. It can be repeated immediately when it ends unless the opponent is airborne. This can be used as a perfect defensive counter against nearly anything, and he can switch to attacking as soon as it's safe. Never mind that his one super stock which gives a buff that almost guarantees half the opponent's life in damage when it connects. Said super also serves as super cancelling move that can cancel pretty much everything you do, most notably a part of your special moves to extend combos, and OTG's or Wallbounces. It also reduce damage scaling, AND disallows damage cancelling. This translates into Zaraki's simple poke(which is pretty good) leading into a nasty, massively damaging combo. To make matters worse he also has a Rushing Slash that gives Super Armor and Wallbounce. In addition to all that he has an invisibility special that offers a nasty mind game, and when combined with all his other moves you know what can or will happen.
In another Bleach fighter, Shattered Blade for the Wii, there's Uryu Ishida. The only character in the game with a naturally ranged weapon (which tells you something already), he has exactly one move that doesn't involve hitting from a distance - instead, it pushes you away, where he could resume hammering you with guard-breaking power shots. A halfway-skilled Uryu player could also make use of his special delayed-release arrows to attack and defend at once. And that's not even counting his Super Mode, which throws in Flash Steps and gigantic lasers.
Also on Shattered Blade, we have Sosuke Aizen. Again. Bear in mind that specials are performed by holding the B Button, and swinging the wand of the wii remote vertically, horizontally, or in a stabbing motion. Sosuke Aizen's stabbing special is to negate any enemy attack by releasing Kyoka Suigetsu, and immediately performing an unblockable counter. This can be performed Ad Infinitum, meaning you can win a match without taking damage.
Soul Codes in Heat the Soul 6 are pretty broken. Neliel's nullifies projectiles, Zomari's gets rid of your opponent's partner, Aizen's restores your Reiatsu at an absurd rate, and the list goes on.
Marvel vs. Capcom 2 has Storm, Cable, Magneto, and Sentinel, who are so ridiculously overpowered that fans refer to them as the "four gods". These characters have a high amount of infinite combos and exploits that completely destroy the rest of the cast. To make it even worse, there are over four-dozen characters in the game, most of whom are either near-useless in comparison or good only as assist characters.
As far as Cable goes, four words: "AIR HYPER VIPER BEAM!!!"
A bit off-topic, but that's actually pretty accurate to the comics for those characters' power levels (at least, in regards to the X books).
They are also projectile specialists who excel in long-range, which was how to own that game. Many an expert player call up a team of Cable, Gambit, and Cyclops, then beat the story mode without ever having to leave the left side of the screen until Abyss.
There are also the characters that tend to never show up except as assist characters, but kill the fun for new players just as much: Cyclops, Captain Commando, and Psylocke, whose dominating assist attacks make up for their mediocrity as point characters.
Strider is also seen paired with Dr. Doom as an assist to execute a devilish trap which can keep the opponent in perpetual blockstun, rendering them unable to move while they take chip damage. As an added bonus, unlike many characters who have dominating assist attacks Dr. Doom is considered a High Tier character in his own right.
Iron Man has all sorts of nasty tricks, in addition to being Magneto Jr. There's a good reason why he's High Tier folks. Blackheart does some nasty shit as well.
Tron Bonne's projectile assist is glitched as well and does more damage than the programmers intended. Because of this her assist sees some tourny play.
Sentinel looked to be one again in Marvel Vs Capcom 3, due to his high health, high damage, high range, high amount of super-armor frames, fast dash/wavedash, good air maneuverability, amazing projectiles, assist moves, and easy combos. Luckily, there are a few anti-Sentinel strategies being created to exploit his weakness to rushdown (His slow attack startup makes him weak at extremely close ranges), but Sentinel was a massive threat until...
... A patch that decreased Sentinel's health by almost a third, giving him around the same HP as Viewtiful Joe. This, combined with more people taking advantage of his massive size and very slow attack speed, has made him much more of a tolerable threat. The game's game breakers at the moment are now considered to be Phoenix and Wolverine (the latter arguably qualified as a game breaker in every other Marvel vs. Capcom game except MvC2). Phoenix is extremely fast, has an amazing teleport, has fire balls that home in on you and prevent almost any significant forward movement all at the cost of laughable health... until you do land that hit and make her transform into Dark Phoenix, where she gains even more power, chips life away very easily and boasts the same extreme mobility of her normal self. Wolverine is extremely fast, very powerful, has one of the most useful pressure moves in the game with his dive kick, can use his Berserker Slash for easy mix-ups and destruction of any zoning attempts, can use his Berserker Charge to make himself even faster, and can even create hyper combo loops with his Tornado Claw to kill characters from 100% life.
And then there's the DHC Glitch. When a character puts their opponent in a "grabbed" state, then cancels their Hyper Combo into one of their teammate's (referred to as a Delayed Hyper Combo or "DHC"), and that hyper utterly fails to hit the opponent, the damage scalingnote As you chain more hits together in a combo, each succesive hit does less damage. This is in place to prevent combos that easily kill every character, and is common in fighting games. and most of the hitstun scaling for the combo is reset. May sound difficult to do, but most characters have cinematic hypers, which count as a grabbed state, and can be cancelled into other hypers as normal. This means you can start a combo that ends in a cinematic hyper and does at least half of your opponents health, then cancel it into a teammate's hyper that doesn't hit (such as, say, a power-up hyper), then while the opponent is recoveringnote When you cancel a cinematic hyper, the opponent is launched a bit into the air for long enough for a hyper to fail and the one who used it to regain control of their character have that character do a combo to finish them off. Tournaments are basically first one hit loses that character. Thankfully this has been fixed in Ultimate Marvel vs. Capcom 3.
Ultimate, however, has brought in something Phoenix, Wolverine and the DHC glitch wish they had the power of. Meet Albert Wesker, who was already a very powerful character in the original MvC3. The character has a very fast teleport attack that gives him a fierce mix-up game, and he can cancel into this teleport off a shot from his gun. When a mix-up lands, his very high damage output will shave into your character's life bar very quickly. His normal attacks have gigantic hitboxes on them and are incredibly safe and easy to hit-confirm. He himself has slightly above average health, so it isn't that easy to kill him fast. He also has several counter moves at his disposal and has one of the best assists in the game in the aforementioned gun. What sets Wesker so far apart from the other powerful characters is that when his sunglasses come off (by taking damage... or, just landing his Phantom Dance hyper) he becomes faster and stronger than before, allowing him to easily kill characters from 100% life. He's very fast, very strong, difficult to defend against, difficult to keep out, difficult to kill, a very easy character to make huge comebacks with and outclasses a ridiculous amount of cast members (although not quite to the extent of the four gods... ish). Thankfully, tactics have been developed to counter Wesker's many shenanigans, though he's still considered high tier at worst.
Nearly half the cast has infinites thanks to a team aerial combo glitch that causes the game to not reset hitstun scaliing, allowing characters that have at least decent aerial mobility to keep attacking the opponent until they get KO'd. However, this is less practical than it sounds, as the timing needed to be able to pull off these infinite combos is so tight that you'd need to be like a robot to actually pull this off in a tournament or online.
Wesker has been relieved (to an extent) of his Game Breaker status...only to be replaced by Morrigan. At first, she seems like a fairly average character, until you figure out her Soul Fist fly/unfly cancel. This tactic, combined with her Astral Vision super and Dr. Doom's Hidden Missiles assist, can fill the screen with projectiles and make it extremely difficult to advance towards her.
Capcom vs. SNK 2 contained a glitch somewhat infamous in the tournament scene - by quickly cancelling a roll's opening frames of animation with a special move, the character was rendered invincible for most of the move. America's reaction was to ban it in tournaments, but it was not banned in Japan, leading to a rather sad display in the major international tournament when Japan walked all over America. Now, "roll cancelling" is generally required to play the arcade game competitively, although the glitch was fixed in the Xbox and Gamecube Updated Rereleases.
The first Capcom vs. SNK had a ration system that totally broke some characters in the game. Nakoruru in particular is considered to be one of the most broken characters in any fighting game ever.
From Tatsunoko vs. Capcom: Soki. Sure he doesn't seem cheap, but once he goes into his little transformation, he throws all of the rules out the window. He can heal, doesn't flinch unless he is hit by the strongest attack (one that takes 3 bars of energy to execute), and worst of all, his aura suggests that everything he is doing is fair. Don't ask me how. Just play against him and you'll see what I mean.
His standing L is also another reason why people consider him to be cheap: it's a ridiculously quick sword poke with tons of range that can also cancel into itself and used to start his combos and thus any character without projectiles has great difficulty approaching him.
Also Tekkaman, considering his super moves are incredibly easy to accumulate, very powerful, can be done from a distance, and extremely hard to completely dodge, which means that even if they're blocked, the chip damage alone is sufficient.
Yatterman-1 has super attacks that automatically put him on this list considering how fast and powerful they are. His Yatterman Charge is so broken that it can take down the Final BossYami, in all three of his forms without even breaking a sweat.
By far the most broken character in the original release of TvC, Cross Generation of Heroes, is Karas. His pressure game combined with his speed created nearly inescapable corner traps. If on defense, you had to do everything you could to get out of the corner when fighting him or it was a doomed game. Thankfully, his speed has been significantly reduced for the update Ultimate All Stars and thus has been brought down to a more reasonable level.
Gundam SEED Destiny: Alliance Vs. ZAFT II has two variants of the Strike Gundam banned from Tournament Play in Japan. The Strike Noir Gundam is a Lightning Bruiser with excellent offense and defense, good ranged attacks, nice melee options, and no real defects to speak of. The Launcher Strike Gundam is a Mighty Glacier ranged machine that possesses the ability to cover its landings, making it nigh-impossible to approach and counter.
In Gundam vs Gundam, the Strike's successor, the Freedom Gundam, is literally the god unit of the game. While its weapons list is fairly standard, its S.E.E.D. ability allows it to perform an instant dash-cancel, allowing a skilled player to rapidly set the distance of a battle as well as providing insane combo potential. As part of its rebalancing, the sequel gave this ability to every unit (under the name "Next Dash"), which only served to make the ∀ Gundam a Game Breaker in its own right.
In Gundam Extreme Vs., the 00-Qan[T] has fast melee moves and Attack Drones that can quickly knock down an opponent or form a shield that blocks everything, as well as a Super Mode that heals it upon activation and gives it a powerful full-map beam attack. To a lesser extent, the Susanoo thanks to its insane melee combos, Crossbone Gundam Full Cloth for being an all-around Lightning Bruiser, and Tallgeese III thanks to its heat rod being fast enough to punish just about any attempts at close combat. All of these received rebalancing in the sequel Full Boost, though for the Susanoo this entails shifting it up a tier.
Emerl's Ultimate skills in Sonic Battle. During the last part of the game, you can get these skills that are ridiculously powerful. However, thanks to the game's Skill Point system and each of the moves' high cost, you can't have them all on at once without the use of a Game Shark.
Not to mention how ridiculously hard it is to get them without a Gameshark.
This is neutralized by the fact that Emerl is the weakest character without insanely powerful moves, so the reverse of him being the strongest character with insanely powerful moves must be true as well.
Tech Romancer has a basic game mechanic called the Iron Dash, where your Humongous Mecha rams the opponent. It does no damage, but leaves the victim open to a follow-up attack. This includes any Limit Break and even the mech's Final Attack. Once a player beats their opponent down enough to activate it, they're one Iron Dash away from victory.
In Wii Sports boxing weaving back and forth repeatedly, then countering when you foe misses results in such easy wins, the player can literally reach a rank that is off the scoring chart, and if they go at it long enough, off the screen.
Also in Wii Sports, returning a tennis serve at the right time makes it impossible for the server to hit the ball back. With a little practice, games of tennis can turn into "Receiver always wins".
Also in Wii Sports, it's easy to get a strike every time in bowling by throwing the ball up in the air when you bowl. The ball rolls down the lane incredibly slowly, but very rarely has any spin at all.
BlazBlue has its resident Robot Girl, Nu-13. When played in melee (as in the 2009 Arcade Infinity finals) she's balanced (somewhat - the reach and priority on her C-attacks is far better than they should be). However an expert Nu player will use her knockback and teleport moves to avoid melee at all costs. Staying at range lets her play defensively, and abuse her absurd projectile combos. While BlazBlue's system does penalize excessive defensive play, Nu is allowed to stay defensive longer than any other character before being penalized. Longer even than Hakumen, who's meant to play a defensive/counterattack game.
Not to mention the infinite combo on Carl, is not subject to the combo rule on BlazBlue because it contains a throw, which means he's rather nasty in the hands of a skilled player. See here for a good example of the loop.
Ice Car must have been nerfed in Continuum Shift, because now all Jin does is spam his ice swords until he gets a health advantage and then run away waiting for the time to run out.
And of course, all the unlimited characters. Essentially, these are alternate forms of the characters that take their advantages and crank them straight Up to Eleven. For example, Ragna is in constant Blood Kain with a larger health bar, all of Jin's specials are the drive variant with no meter cost, Arakune can instantly curse you and his bees are almost the size of Carl, and Tager gains two spark bolts and a greater magnetism radius. But the real "fun" starts with Hazama, who has a perpetual green aura surrounding him. Should you touch this, you will lose health as long as you are in contact with it. And all of that health you lose? Yeah Hazama gains that much added to his own health meter.
Unlimited Taokaka, whose Drive attack can take OVER 50% OF YOUR LIFEBAR AWAY. AND YOU CAN SPAM IT AT NO COST!
Someone discovered Noel's extremely broken single-move combo that can be kept up without a break. Her 2D drive; an overhead flip that fires the guns downward into the enemy, causing the target to get stunned for a moment - even the cancel/recovery takes long enough for the next attack - and can be continuously spammed once the player on the receiving side runs out of bursts. Of course, the first hit has connect without being blocked or else it can be countered. But as soon as the first it connects... You then realize you can continue doing it and keep on looping it until the opponent's life bar rests at zero. Never mind the gold and green bursts or blocking and barrier, mistime the blocks and you'll get owned. After the bursts are all gone... et tu, Brute?
In Dragon Ball Z Budokai Tenkaichi 3 there is Tien, with his Neo Tri-Beam. The attack, which is his ultimate, is nigh-on impossible to dodge consistently without being lucky enough to fall behind an obstacle. Once it hits a target, that target is forced into its "falling down" state, and is unable to move until the attack is over. This wouldn't be a problem, if it weren't for the fact that this attack can be fired more than a dozen times in one activation, enough times to kill ANYONE who hasn't been enhanced for higher health. Suitably enhanced, Tien can fire this attack as his second action in battle (the first being charging to Max Power).
The main Game Breaker in the Tenkaichi series comes from the first game, as Krillin's Destructo Disk special. It's almost impossible to dodge at medium range, as it goes wide and then crosses you at a huge speed, and can go straight up! He was also one of the first characters you fight in story mode (as training for the actual fight against the Saiyans) so, needless to say, you got a crash course in dodging.
In Budokai Tenkaichi 2, one version of Vegeta could Beam Spam for just one energy bar. Even without charge-quickening upgrades, he was still deadly just by spamming it.
And then there's Great Saiyaman 2, a.k.a. Videl's powered-up form. She has an attack called Justice Countdown that, unlike every other rush-type Blast 2 in the game, has zero lag in execution, and to make matters worse extends the opponent's hitbox just far enough to make it completely impossible for them to intercept the move, or even block it. It can be dodged, but this requires god-like reflexes to the point where it seems only the AI opponents can ever pull it off, and it probably says something that even THEY usually don't. On top of that, the speed at which a fighter gathers energy is based on the fighter's raw power and is meant to balance the game; fighters like SSJ 3 Goku gather power agonizingly slowly, whereas Hercule has one of the fastest charges in the game. Because Great Saiyaman 2 is viewed by the game as a "weak" character, her charge is fast enough that she can spam Justice Countdown, as 2 energy bars are filled in less than a second. Making matters even worse is the fact that she has After Image Strike as a Blast 1, which allows her to dodge virtually any attack, even Beam Spam. And unlike the other characters with After Image Strike, she can do it for 2 energy bars, whereas everyone else requires 3 (and on longer charges).
Videl/Great Saiyawoman's abilities are neutralized due to the fact that she is completely helpless against giant characters.
Super Saiyan 2 Gohan is one of the fastest characters in the game, hits like a truck, has great ki control, and has great stock moves along with one of the most powerful ultimate moves (Father-Son Kamehameha) in the game that can be powered up using his stock move "Unforgivable" to do obscene amounts of damage to any opponent he faces.
Yajirobe, in all of his glory counts for this. He has good attacks that allow to fight up close or at a distance, great ki control, and the best thing about him is he has the fastest stock recovery of all the characters in the entire game! His Level 3 stock move is "Super Unyielding Spirit" which automatically gets him to MAX POWER and his level 5 stock move is "Senzu" where he eats a senzu bean and recovers all of his health. It gets even worse when you consider his ultimate move (Miracle Ka-Blam Slash) is one of the few rushes that can hit giant characters, and you realize that Yajirobe is practically the definition of this trope.
Great Ape Baby is a definite game breaker. He's a giant character, meaning he's resistant to knock back from most characters, cannot be thrown, is immune to most rush-type Blast 2/Ultimate Blast attacks, and has high attack/defense/blast stats. Unlike other large characters, however, he has low energy requirements for his beam attack, he can recharge his energy quickly, and he is very fast. This is so much worse when he's controlled by the computer.
If you're talking about Game Breakers, then you have to include Majin Vegeta, Legendary Super Saiyan Broly, and Kid Buu. Yes, these guys are supposed to be strong in the series, but these guys take it to the next level. While most Super Saiyans are somewhat balanced and make up for their impressive strength with slow to average ki recovery at best, these guys have some of the fastest ki recoveries in the game as well as crazy strength. They also have stock moves that can instantly make them reach MAX POWER, without becoming fatigued and having slower ki recovery than normal afterwards. As for Kid Buu, he has some of the best attack, speed, and ki recovery in the game, and has a stock move that can recover him back to full health. All three of these characters have special projectile moves that can take around a bar or more of damage, and their super moves are so powerful they can destroy the planet. Even if Majin Vegeta's super move causes some serious recoil damage, his basic move set is so broken you probably won't even need to resort to it.
Bardock is no slouch, either. In addition to having Wild Sense (which acts similarly to After Image Strike) as a Blast 1, he possesses two very powerful ranged specials that can deal over a single bar a health without needing to be charged. As long as the opponent has been sent flying first, these atacks will almost always hit.
Dragon Ball Z: Budokai 3 has several Game Breakers as well. The most obvious ones are the "revive" capsules, Frieza's/Cooler's Spaceship/Babidi's Mind Control. Essentially, they revive the fighter when dead to FULL health and Ki, in addition to making them far more powerful than they were to begin with (for instance, Majin Vegeta has an instant kill move). Less obvious is what I call the "Broken Combo": Viral Heart Disease/Vaccine/Yakon/Gero's Deflect-back R&D .This combo automatically drains most of an opponent's health while making it INCREDIBLY difficult to fight transformed (i.e. as a Super Saiyan), all the while automatically sending Ki Blasts back at the opponent by blocking. Add this to Dr. Gero, who can absorb Ki Blasts anyway, and you have the formula for broken.
Super Saiyan 4 Gogeta. His Ultimate Move, 100x Big Bang Kamehameha, takes off THREE life bars if you win the attack struggle. That's (usually) enough for a one-hit kill. Unfortunately, though, you only get to use him once in the storyline, and fusion is banned altogether in the tournament. Still, he's powerful enough that in the one time you do fight as him in Dragon Universe (against Omega Shenron) you can basically do an Ultimate Move straight away and win. (And doing this nets you a Story Reenactment, too). Adding to the broken-ness of this character is the fact that you CAN'T fail the fusion (unlike the other fusion characters), though admittedly it's pretty easy to execute a fusion anyway.
Raging Blast has its moments, too - particularly Captain Ginyu in Team Battle. You can fight with him until his health is low, have him use Body Change to regain health, switch to another team member, switch to a THIRD team member (or have the second transform if the situation allows), and then switch back to Ginyu. He will be in his own body again, and thus be able to use Body Change again. Until the other fighters in your team are beaten, you can essentially make Ginyu immortal.
A great Game Breaker in Raging Blast 2 is equipping Guldo with Unexpected Blow and anything to increase Ultimate Attack damage. Charge him up to High Tension, activate Raging Soul, and you can use the Guldo Special up to four times in succession. Since the attack is unblockable, difficult to vanish from, and homes in on the victim, this is a huge game breaker to those who don't know about timed hits.
Goku himself is a game breaker in Raging blast 2. It comes with the territory when your most powerful attack can only be accessed in the base form (and there is no energy struggle or combo necessary like in previous games). Goku also has a Kaioken finish, a high priority attack which guarantees an opponent's health bar which out using too much of Goku's energy.
No love for Infinite World? Yes, the same gamebreaker of Budokai 3, Gogeta (both Super Saiyan 2 and 4 versions) and Vegito are there, as is Omega Shenron, but these guys pale in comparison to Baby Vegeta. How broken is he? You know Vegeta's super moves, Final Flash (only capable of being done from a successful Dragon Rush) and Big Bang Attack? Baby Vegeta can spam those as regular moves! On top of that, he has a super on par with other fighter's super moves. The only characters that really stand a chance against him are Super 17 and Janemba, and even then, you have to get lucky.
The characters in Little Fighter 2 are fairly well balanced with the exception of Louis. At first appearing to be the Mighty Glacier, Louis is the slowest character, but does above average damage and blocks hits with his armor 50% of the time. Good, but not excessively so. Then you find out using his transformation move when he's on less than 25% health causes him to lose the armor, but it vastly increases his speed, and he gains a spear that gives him the best reach in the game and can spam instant-hit undodgeable ranged attacks that knock back multiple targets. And the transformation move itself is uninterruptible and deals damage.
Rudolph and his clone-spamming Multiply technique, which summons several copies of himself with the same capabilities and lower health. Once you get enough of these on the screen, even a single clone becomes abnormally sturdy and difficult to take out. Luckily, there was often a pact among friends to simply abstain from using him altogether.
And with a bit of extremely simple text editing (seriously, you just need Notepad), you can play as the game's boss, Julian, who has a three-burst homing attack, an energy ball attack that plows through dozens of enemies and is unblockable, and an explosion centered on himself that sends enemies sky high while dealing incredible damage. The best part? Each of these special attacks cost so little energy that spamming them is incredibly easy. Oh, and his normal punches do about as much damage as the sword blows of one of the other main characters. One can easily wipe the floor with the above Louis EX with Julian.
Wait, you mean playing as the final boss is unfair?
Even simpler than that. If you just type in "lf2.net" when the game is loading, all of the characters will be unlocked. Which of course means you could also play as Firzen from the start.
One of the first alternate versions, R-LF 2, is practically MADE of this trope. See, every character in the game (yes, even those Mooks you could kill with ease) are given new attacks, and have their old combos re-vamped. For example, remember that crappy fire-breath move Firen had? Well, now instead of occupying 2-3 spaces it stretches about 2/3 of the whole screen. Not game breaking enough for you? Ok, how about if I told you that every character also has a hidden "Hell" move, that pretty much ends the fight once you use it? By hidden, i mean it requires a unique multi-key combo to pull off, and under a set amount of time as well. While this sounds like it evens things out, some of said combos are so ridiculously easy to pull off it's almost laughable. Case and point: those purple explosions Julian's Soul Bomb causes when they hit something? Well, Julian's Hell move consists of just that one explosion. That multiplies. As a whole wave of explosions. That start from his position and move both ways, enveloping the entire screen. Now imagine your character caught in that maelstrom of explosions. Yeah.
AND if you thought that the Final BossJulian in Reinforced LF 2 was cheap enough, then you haven't seen the secret character Conrad yet. Remember those deadly columns that Julian could create? This guy creates an entire wave of them, on BOTH SIDES. He also has many other broken moves, especially the Hell Moves- one of which summons a purple dragon that charges the crap out of enemies multiple times, another makes him delete one victim from the game (works on the FinalBoss, by the way), and another makes him trap enemies with homing columns of dark energy until they die. As for defensive abilities- Conrad regenerates health faster than anybody else, and to top it all off, he gets Mercy Invincibilityevery time he gets hit. In short, Conrad makes Julian look like a complete joke, and that's saying something.
Firzen in a particular version of little fighters (Little Fighter 2 Kate version...) has a move that requires a small bit of his health and mana and sends all enemies on the side he is facing into the skies burning and freezing as though they hit an invisible wall of fire and ice. If that wasn't enough, another key click and he apparently cuts them in the air with invisible blades all off screen, sending their burning/freezing (mostly likely dead or nearly dead) bodies flying from off screen away from Firzen. Also, Arctic Volcano in the regular version already nearly insta-kills anyone near him. In Kate version... ...you can continue this until your run out of mana... or you can add the F5 key (infinite mana) and continue until everything is dead.
Kate from this particular series (looking like a person wearing a Pikachu suit) was made to blast everything in the way of the attack into oblivion with its multi-hit arcing thunderbolt attack, which is one of the regular special moves it has. Not to mention that special move has a huge range and the tendency to drag the target along with it.
No one ever mention Firce777? He's probably the most broken mod character. He shoots a wave of fireballs and wave of iceballs in front of and behind him respectively, while standing. He shoots a wave of arrows, explodes and spawn tornadoes when walking. He can also spawn five Firzens as well as five energy discs and increase his mana by a little bit (the creator names this move "Five Loaves Two Fish"). And for the worst part? He can turn invisible for free and cause his Firzens turn invisible as well.
Eternal Fighter Zero features two SNK Bosses, but only one was de-powered for the playable version. The other, Kanna, retains all of her insane range and priority attacks, and is thus usually banned from tournament play.
In Custom Robo for the Gamecube most if not all the illegal parts fall under this trope. The most egregious was Rahu III and his associated parts. He is the only robo who is immune to the fallen state, where a robo drops to the ground and is unable to do anything and the enemy can pound away at it. The Rahu III body takes only 20% of normal damage from all attacks. To top it off all of his weapons are extremely powerful and have an enormous blast radius.
The X laser illegal gun to a lesser extent when you use it right. Technically it is noted to have a weakness when you fire it at point blank range but that only applies IF the opponent is already within your attack radius with a faster gun (few are faster). The X laser can not just fire around obstacles but it has a high downing rate so it takes about 1 or 2 shots to down your opponent. A skilled user can just sit in one place and pluck your opponent down at his or her leisure.
Another is the Wyrm illegal gun. Thought Dragon was powerful? This gun lets you fire FOUR OF THEM AT ONCE. From the air it also alleviates the Wyrm's single weakness by firing a single high speed shot at the same face value.
Another self discovered combo is the Athena Raptor gun illegal combo. Normally when you fight the Athena models, you are fighting them with a Waxing arc or a waning arc (left or right curving guns). Now while those guns are awesome, it doesn't actually play to Athena's strengths. Athena has 6 additional jumps. With the right timing, one can reach the top of the screen EASILY with Athena. That is where the Raptor gun comes in. When you are in the air, the Raptor will fire a standby round that stays in place. Now the number of rounds you can keep up at once is about 10 at a time because at that point they start firing and you shoot at the rate they start dropping. Now while this doesn't make it broken, it is the fact that you are effectively SLOWLY dropping as you fire this gun. By the time you reach the ground, your opponent will be full of holes and by the time they raise their gun to shoot at you, you'll be back in the air already.
Can be extended further with a Lightning sky model, the MOBILE extension to this trick. Now you can fire like crazy while not being a stationary target.
The Crystal Strike illegal gun. Just mashing the fire button can send an unending stream of death at your opponents, and if just one hits, they ALL hit.
Stun Gun + Formula Legs + Peregrine body (a Fragile Speedster) = a robo that can pin an enemy and stun the everloving crap out of them. I have seen several hundred hitpoints removed by one of these robos in under a minute.
If you think any of that was bad, try using the knuckle gun on one of those robos in exchange for the stun gun. The knuckle gun was exceptionally hard to use, but if you managed to learn it, it would be quite easy to take out over 400 hp in a matter of seconds.
In the Naruto Ultimate Ninja series, there is a game breaking trick in which if you charge up your super move while an opponent plane shifts toward you and you're the proper distance from them, you can time the initilization of your super move just as they come down. Since you're briefly helpless during this, if your opponent does this trick, they get a free hit. This trick is difficult to counter if done correctly.
The speeding dash into your guard, that leaves them open to a special jutsu. Hurray for AI lag. Oh, and Tenten and Kurenai are insanely broken. Tenten can fling anything out and had some heavy items and an array of dakka enough to bring even Sakuya to shame. Kurenai, however, has some attacks that make her disappear, keep her opponent at range while she stays stationary, has a bomb attack that just EXPLOES in your face, and some drill lock speed combos. Also of note is Ino, who has insane drill lock combinations and speed. She can also poison you, and places herself in some posistions where it'll be a miracle to hit her.
The ultimate game breaker in the PS2 games in this series is button locking. By performing a quick dash, knocking your opponent up into the air, and then throwing kunai at your opponent. This causes the opponent to not be able to register any button presses, leaving them vulnerable to level 3 specials.
The lastest game, Naruto Shippuden: Ultimate Ninja Storm 2, gives us Deidara, who can kill you from across the screen without leting you get close by spamming his laser guided bombs, which can stop your chakra dashes or attacks, and using chakra back dash to keep out of reach.
Also in the Ultimate Ninja Storm series, the Left Stick Flick attacks. Most people don't know how to do them because of the bad instructions on the control menu, but once one figures out how to do them, they break any fight. In the first Ultimate Ninja Storm, as well as Generations and Ultimate Ninja Storm 3, Part 1 Naruto's is particularly infuriating, as it covers a large distance, can be spammed endlessly (due to the attack type not using any chakra), and the user can then run while the clones keep the enemy at bay. Did I mention it also cuts chakra dashes, launches insanely quickly, and does relatively decent damage?
One Must Fall 2097 featured a gamebreaker using the Shadow robot. If you stun your opponent, grab them with a shadow double and perform a combo on them, the enemy will only get up stunned again, allowing you to repeat this ad infinitum. Effectively, so long as you can stun your opponent once and perform this trick, you win.
A similar trick could be performed with the Chronos robot if you froze your opponent in the air, combo them and froze them again rendering them absolutely helpless. Even the CPU on Ultimate difficulty could be taken down easily using this method.
In the Star Wars: Episode 3 game there was a Love Interest of Mace Windu who used 2 lightsabers. She was SUPPOSED to be a defensive character, and there had the best run speed. However her attack animation is quick, and consists of hitting the enemy on the head, causing some stun... and letting your follow up. Only that attack causes stun too. So you can keep attacking, and keep spamming, easily outclassing even the offense specialist. Except if they try to break off, you can just chase after them and start spamming again. Her attack power is only a little bit below average, but it's INSANELY easy to make the both hits connect, and to start a flood of hits, letting you take out a good portion of the opponent's health very quickly. Its possible with good timing you might even be able to make an infinite combo. I was only playing for about 10 minutes, and the best I did was 60% health in one combo, before I stopped picking that character out of politeness.
In the WWESmack Down vs Raw series, as the games evolved and improved things like blocking and countering mechanics and collision detection, some moves that had been present in the first game were never updated, and still played the old sloppy way. When Smackdown: Shut Your Mouth introduced online play to the series, players discovered that a lot of the older moves couldn't be blocked. The "women's toe kick" and "diving headbutt" being two of the most notable and abused. While most players refrained from using them, some went the other way and sought out every single glitchy or unblockable move and called anyone who complained about this a scrub.
Tangentially related to the above: in the old, old, old WWE game WWF WrestleMania Challenge for the NES there was Andre the Giant. Andre was fine enough to face with the computer controlling him in "Championship Mode", but when playing two player versus, one of Andre's moves was the bear hug, executed simply with the B button, the bear hug had no maximum time it could be applied, it was uncounterable, and there was no way to escape it. The player playing Andre could slap it on, hold it until the other player's stamina was depleted, then pin the guy. Oddly enough, the computer wasn't cheap enough to employ this tactic, even thought Championship Mode's Ultimate Warrior was an SNK Boss.
The main reason why the omniblock does not work on those attacks is generally because that attack either strikes from directly above or below (where Omniblock does not guard against), has a disjointed hitbox (bypassing the guard altogether) or with a discrepency in the execution (where it can be blocked but not reliably). That said, they are not so much as counters as they are attacks that just happen to have strange properties. Examples include Zidane's Free energy which activates VERY FAST and hits at the target's exact location and Cloud of Darkness' Aura ball which does not count as HP damage until they explode and you can sneak one past the shield without triggering it(although gouging the distance is the problem).
In a more benign direction, there are circumstances which, if stacked properly, let you zip to Level 100 in one fight. It's generally called the "Exdeath cheat"ónot because it depends on him, but because his particular flavor of Artificial Stupidity is the easiest to work with while you're setting up the in-battle conditions that make it work.
Exdeath is...well, he's still as amazingly powerful as even in Duodecim, but a new addition may have dethroned him from the title of Resident Game Breaker—you see, Exdeath is still allowed (indeed, almost expected) in tournaments. [Via Dolorosa—er, Feral Chaos, is not.
Battle CAPacity formerly had Pyroak as absurdly difficult to fight, thanks to incredibly effective projectiles, a grab which knocks the opponent away if they approach, the best anti-air move in the game hands-down, and Wood Hammer. Wood Hammer is an overhead attack which comes out absurdly fast, shuts down reckless offenses, and screws over turtlers which can't shift to a high block in time. He's been nerfed to a degree, and while he has the best matchup against one of the other Game Breakers, he isn't absurd.
Speaking of the other Game Breaker, Revenankh. Rev has the best wake-up game in Battle CAPacity by a wide margin, with a wide variety of powerful grabs, including an air grab, an anti-cornering attack, and one of the other best anti-air attacks in the game. He also has very safe approaches thanks to Shadow Punch and Bind, and can combo Shadow Punch into his close strong, followed by said anti-air, then his air grab (25A/B, c.5C, 4B, j.G). He gets mightily screwed over by Pyroak, however, thanks to his projectile trap. Like Pyroak, he's also been nerfed, but is still considered one of the best characters.
The current contender for Game Breaker staus is Skulloton, whose boomeranging projectiles, launcher combo, and excellent comboing abilities allow him to tear huge chunks of the opponent's life bar off very quickly.
The lesser-known fighter Battle Blaze on the Super NES featured a quick AI that was able to tear you apart in seconds if you let it. That is, until you discover the magic of the relatively simple "Forward+Y" move. While essentially a throw, all characters are quick enough to run over to an opponent and grab them the moment they are standing upright again! During "The Hero"/story mode, you can keep throwing the computer opponents the moment they get up with very little retribution, if any. This "throw" even trumps any attacks they might use, allowing you to gain perfects on opponents up to and including the final boss with only minimal effort!
Older Than The Nes: The Way Of The Exploding Fist. Since the game uses shobu nihon kumite scoring, the priority is knocking the opponent over rather than wearing down their energy bar. In real karate, the leg sweep is perfect for this. In Fist, the leg sweep is a little too perfect; the first ten levels can be completed with nothing but the leg sweep.
Elsa in Arcana Heart 3 has several infinite combos, depending on which arcana is selected.
Touhou's Immaterial and Missing Power spin off grants us Patchouli Knowledge, probably the easiest character to win the game with due to how in-game bosses react to one of her attacks. Sun Sign "Royal Flare", one of her second signs in the game, hits all around the screen for an obscene amount of damage. Due to the way Spell Cards are declared, you can build up 9 cards on your first life and then spam Royal Flare on your second; note here that you have to die twice in order to lose a life (they have to beat both of your spell cards), so losing once per fight is practically meaningless. Even if the enemy survives those 9 Royal Flares, the Spell Card System allows you to farm for more in the same life. Player spell cards cannot be canceled once initiated, leaving the opponent with the little time between cards to counter. Even if bosses could block during their spell cards, both grazing and blocking have a finite duration, so they would eventually fall prey on Royal Flare due to guard breaking or them just plain stop grazing out the damage. Patchouli still has Royal Flare as her spell card on subsequent fighting spin-offs for the same effect, but the new system restricts it to a maximum of 4 declarations, once per card equipped, at the highest casting cost.
Sonic The Fighters has Sonic's spin-dash move. Even on the hardest difficulty, this move will mow down any of your foes like a hot knife through butter, due to its excellent damage and the recovery time it has your enemies go through, with the possible exception of Metal Sonic. Even if you block it, a direct hit will STRIP OFF THREE BARRIERS! The default number of barriers you have is three and you can have a maximum of five depending on the settings and almost all the other barrier breaking moves only break one of them. If you let Sonic(Or Tails, Knuckles or Espio) hit with a Spindash twice, then you're pretty much defenseless for the rest of the match.
Ickybod Clay and Taffy in the original Clayfighter, due to their incredibly long reach.
Gage Novus in the original Forsaken Chronicle due to the sheer speed and damage output of his moves and the infamous Hell Step which involves a lightning fast, heavily damaging, stomp that stuns your opponent on the first strike, knock them to the ground on the second and can hit them on the ground anyway. Four of those can kill Unit Alpha and Connor Omega (Who have the highest HP other than Gage Novus).