ZZAZZ glitch

The player encounters one of several glitch Trainers which can trigger the ZZAZZ glitch.

The ZZAZZ glitch is a data-corrupting glitch found in the Generation I games that occurs when the player encounters a certain glitch Trainer.


In Pokémon Red and Blue it can be triggered by using the Ditto glitch with a Special stat of 248, 251, 252, 254 or 255 and without altering the Attack stat. In Pokémon Yellow the stats of 249, 250 or 253 will also cause the glitch in addition to the above.

The glitch is directly caused by a multiplication routine used to calculate the amount of money awarded at the end of the battle. As money in Generation I is stored as binary-coded decimal, the game must perform several arithmetic functions in order to load the proper value into memory; as part of this loading, the game attempts to ensure that the money value is capped at  9999. However, since the glitch Trainers encountered have an invalid money value unlike normal Trainers, the arithmetic functions fail to behave as expected, corrupting a pointer[1] and causing the byte 0x99 to be written to the first two out of every three bytes for each time the calculated award would exceed  9999 after the first. For the Trainers that trigger the ZZAZZ glitch, this happens over two hundred times, destroying many important game variables.

The glitch Trainer is usually seen sending out a level 153 'M (FF)RB or a Q ◣Y with an extremely long HP bar; attempting to use a move or even just view the party will cause the game to freeze due to the corruption. However, the Trainer can be easily escaped by using any item (as long as it does not display the party, such as any type of Poké Ball); doing so automatically causes the battle to end (also due to the corruption). During and after the battle, the player can see that every Pokémon in their party except each third one has been changed to a level 153 Bulbasaur whose first, second, and fourth moves are all Explosion; the player's name except for every third letter has also been overwritten with capital Z's (hence the name of the glitch). All of these correspond to index number 0x99.

Although the player's name has been corrupted, the OT values of the party Pokémon have not, causing them to be treated as outsider Pokémon. Combined with the fact that most of them are level 153, they will always disobey the player (as not even the Earth Badge is programmed to make Pokémon over level 100 obey), unless the player's name stays the same after the glitch (with a name of ZZ or ZZ<any character>ZZ).

If the player attempts to battle a regular Trainer after triggering the glitch, that Trainer will become a glitch Trainer with the player's sprite. Their name will either be the player's original name, their ZZAZZ-glitched name, or sometimes a different glitched name, and their party will again consist mainly of several 'M (FF) or Q ◣. Attempting to battle this Trainer will not outright cause the game to crash, although attempting to view the player's party still will. Using items will not end the battle this time. The Trainer is almost impossible to defeat, as the player's Pokémon will not obey (and/or will faint themselves with Explosion, causing the party menu to appear and crash the game), and at least one of the Trainer's level 153 Pokémon has an extremely large amount of HP.

Less immediately noticeable effects of the widespread corruption include changes to in-game interfaces such as the menu. If a player attempts to save the game, glitch options may be displayed that could possibly cause the game to crash. This is due to the corruption of memory address D12C (D12B in Yellow) to an invalid value, which controls which two options (such as Yes/No or Heal/Cancel) appear when the player is provided a choice, along with the size of the menu.

The corrupted menu can be fixed by talking to a Pokémon Center nurse, which displays Heal/Cancel regardless of the value and resets D12C/D12B back to 0 (Yes/No) and allowing the player to save the game. Saving is also indirectly possible via changing PC boxes but saving the game with both methods will often make the player unable to load their save file depending on the player's name before the corruption.

The inability to load the game is actually due to a failsafe that treats the savefile as invalid if the player's name exceeds the intended maximum length, which is very likely due to all of the previous corruption. If this effect is bypassed such as by having an original name that was exactly 2 or 5 characters long (since every third position is not corrupted and so the end-of-string character at position 3 or 6 will be preserved), then the game will be able to load the corrupted file without problems.[2]

There is also a ZZAZZ variant of Jacred, caused by using the Ditto glitch with a Special stat of 200 and using Growl one or two times. Because this is a ZZAZZ variant, the battle can be escaped by using any type of Poké Ball, though this is slightly difficult to do as the Bag will be corrupted and almost fully filled with items named " PokéTrainer". However, it is possible to scroll down past the Cancel button, find a Poké Ball, and then use that to escape the battle. After escaping, the player will be in a type of Glitch City. The game will not be able to be saved directly through the menu, because when the party is opened, the game will lock. The city has no PC to indirectly save the game, nor a Pokémon Center where the menu's save option can be restored by healing the player's party.

By pandakekok
This video is not available on Bulbapedia; instead, you can watch the video on YouTube here.


By Newopkmn
This video is not available on Bulbapedia; instead, you can watch the video on YouTube here.


Transform glitchesGlitch TrainersCloning glitchesError messagesArbitrary code execution
Generation I Battle glitchesGraphical quirks
--0 ERRORBroken hidden itemsCable Club escape glitchDual-type damage misinformation
Experience underflow glitchFight Safari Zone Pokémon trickGlitch CityItem duplication glitchItem underflow
Mew glitchOld man glitchPewter Gym skip glitchPokémon merge glitchRhydon glitchRival twins glitch
Select glitches (dokokashira door glitch, second type glitch) • Super Glitch
Time Capsule exploitWalking through wallsZZAZZ glitch
Generation II Battle glitches
Bug-Catching Contest glitchCelebi Egg glitchCoin Case glitchesExperience underflow glitch
Glitch dimensionGlitch EggTeru-samaTime Capsule exploitTrainer House glitchesGS Ball mail glitch
Generation III Battle glitches
Berry glitchDive glitchPomeg glitchGlitzer Popping
Generation IV Battle glitches
Acid rainGTS glitchesPomeg glitchRage glitch
Surf glitchTweakingPal Park Retire glitch
Generation V Battle glitches
Charge Beam additional effect chance glitchCharge move replacement glitchChoice item lock glitch
Frozen Zoroark glitchSky Drop glitch
Generation VI Charge Beam additional effect chance glitchCharge move replacement glitchChoice item lock glitch
Lumiose City save glitchSymbiosis Eject Button glitchToxic sure-hit glitch
Generation VII Charge Beam additional effect chance glitchCharge move replacement glitchChoice item lock glitch
Toxic sure-hit glitchRollout storage glitch
Generation VIII Charge Beam additional effect chance glitchCharge move replacement glitchChoice item lock glitch
Toxic sure-hit glitchRollout storage glitchParty item offset glitch
Glitch effects Game freezeGlitch battleGlitch song
Gen I only: Glitch screenTMTRAINER effectInverted sprites
Gen II only: Glitch dimension
Lists Glitches (Gen IGen IIGen IIIGen IVGen VGen VIGen VIIGen VIIIGen IXMystery DungeonGOTCG GBSpin-off)
Glitch Pokémon (Gen IGen IIGen IIIGen IVGen VGen VIGen VIIGen VIII)
Glitch moves (Gen I) • Glitch types (Gen IGen II)
  This article is part of Project GlitchDex, a Bulbapedia project that aims to write comprehensive articles on glitches in the Pokémon games.