List of glitches in Generation II

This is a list of glitches that occur in the Generation II Pokémon games.

Bug-Catching Contest
In the Japanese versions of, if the player uses or  to leave the National Park during a Bug-Catching Contest, the game creates unstable  data.

Cerulean Gym
This bug was carried over from. In Cerulean Gym, the water tiles have wild Pokémon data programmed in, which allows players to fish. It was already corrected in and it was fixed again in.

Coin Case
The Coin Case glitches are a set of glitches which occur exclusively in the English versions of. They allow the player to run arbitrary code by exploiting an oversight in the process used by the game to print the text box data for the Coin Case.

When the game is played on the Game Boy or Super Game Boy instead of the Game Boy Color, the effects caused by the oversight are more limited.

Battle Tower text glitch
In v1.0 of English (and not v1.1), a glitch causes enemy Trainers in the  to always use the texts of female Trainers. This is due to the game attempting to use the sixth character of the Trainer's name to determine the gender.

Clair gift glitch
In Crystal, if the player whites out due to damage while still inside the Dragon Shrine at Dragon's Den after receiving the, they can return to the Blackthorn Gym to receive the reward TM from Clair. However, due to an oversight, if the player then returns to Dragon's Den and stands on the tile directly in front of the Dragon Shrine's door, Clair will appear again and give the player another, as if they hadn't already received it.

Legendary beasts incomplete OT check
In Crystal, when the player talks to Eusine in the Celadon City Pokémon Center he will report a rumor that has appeared in Tin Tower (Ho-Oh) and leave the building when,  or  appear in the party and/or storage boxes with OT and ID data matching that of the player. Due to a glitch, the English version of Crystal will only check the first five characters of the player's name. For example, if the player's name was “CRYSTAL”, then having the legendary beasts with the OT name “CRYST” and a matching ID of the player will enable the event. This is due to the player names in the original Japanese version being a maximum of five characters long and the English version failing to account for the change.

Pokémon Communication Center
In the Japanese version of, address $A800 in SRAM triggers a script in the Pokémon Communication Center that may be arbitrarily set to values other than 0x00 when the game does not currently have a save file; otherwise, its value is correctly set to 0x00. This causes all sort of bugs, like crashes, freezes, and other random behavior.

While the purpose of this script is not known, it appears to be related to the Pokémon Mobile System GB. In the localizations, although the related code is unused, this issue was fixed by adding a check that looks up the value of address $A800 and automatically resets it to 0x00.

Dude money glitch
In the German version of, the dude that presents how to catch Pokémon can be sometimes glitched for having a full PC Box. Trying to use the Poké Ball shows: ''Die POKÉMON-BOX ist voll. Das kannst du jetzt nicht benutzen.'' This message also glitches the left side of the screen. Another message is shown: KUMPEL hebt  auf!  If this glitch is done again, the player is left with maximum money.

Belly Drum effect
When a Pokémon uses, its is deducted by 50% and its  stat raised by up to 12 stages, ensuring that even the  stat of a Pokémon with an  stage of -6 can be maximized. This is accomplished through executing the command used by by a maximum of 6 times; however, the command is erroneously called once before verifying that HP of the user can be deducted by 50%. This means that if the user doesn't have enough HP to use the move, the Attack stat will be incorrectly boosted by 2 stages. The game will state that the attack has failed.

Catch rate
The status conditions of paralysis, burn, and poison, increase the catch rate by 0 as opposed to by 5.

The only gains a catch rate of 8&times; on  of the same gender and species as the player's Pokémon, rather than on Pokémon of the opposite gender.

The is supposed to multiply the catch rate by 4 on Pokémon that evolve with Moon Stone but instead does this on Pokémon that evolve with Burn Heal. Consequently, Moon Ball does not have any additional effect and always acts like a.

The is supposed to quadruple the catch rate against all wild Pokémon that can flee (a mechanic unique to Generation II), but only does this for three of them:, , and.

Ditto assumption
Any that uses  is regarded as a  in its new form; this means that if the player catches a  or a glitch Pokémon which has used the move Transform or a Pokémon which has used Transform via, instead they will obtain a Ditto. Mew turning into Ditto is not an issue because Mew cannot be legitimately encountered.

In, this bug only affects because  will fail against. A transformed Ditto using Mirror Move will always fail.

Dragon Fang effect
The Dragon Scale boosts the power of moves rather than the Dragon Fang.

In Pokémon Stadium 2, the Dragon Fang boosts Dragon-type moves as intended, while the Dragon Scale has no in-battle effect.

Exp. Share formula
A with the same original Trainer as the player that is sent into  with an Exp. Share held will gain 50% of the experience twice, which, due to rounding, may not equal 100%.

Experience amount
A that gains an amount of experience consisting of five digits will not have the number displayed correctly but this is only possible with an outsider Pokémon holding a Lucky Egg used at the Trainer House. The lowest level required for achieving such feat is 82 for Pokémon with an experience yield of 255, and the lowest experience yield with which this is feasible is 208.

Experience underflow
Level 1 using the "medium-slow" growth algorithm will jump from level 1 to level 100 after gaining a low amount of experience points (less than 54 if the total experience is 0).

HP bar animation
A Pokémon with 49 or more will deplete the HP bar at a slower rate than intended when taking damage. Due to an issue with the order of the code within the game, a value that would help to set a delay that was partially dependent on the maximum HP of the Pokémon instead sets always sets a constant delay that does not change with different HP values. This results in extra delays in the animation updating and prolongs the animation of the bar dropping.

A Pokémon with 48 HP or less is not affected as each HP is equal to one or more pixels of the HP bar, thus skipping any delay.

Leveling past 100
If a is obtained at a level above 100 (101-254), it can be leveled up with Rare Candies up to level 255. If a Rare Candy is fed to a level 255 Pokémon, its level will reset to 0. If a Pokémon above level 100 levels up due to experience, its level will be reset to 100.

Lock-On/Mind Reader oversight
When or  are in effect, the moves, , , , , ,  and  cannot hit targets in the semi-invulnerable turn of  or , and moves cannot lower stats of targets in the semi-invulnerable turn of Fly or Dig (status moves such as  will fail, and additional effects of moves such as  will not activate).

Opponent Full Heal and Full Restore oversight
If an opposing Trainer uses a Full Heal to cure their Pokémon, it will not be cured of (even after waking up from ) or of.

If an opposing Trainer uses a Full Restore to cure their Pokémon, it will not be cured of (even after waking up from ). However, it will be cured of.

The Full Heal and Full Restore properly cure a Pokémon of both Nightmare and confusion if used by the player.

Park Ball graphics corruption
If the is used from the Ball pocket of the undefined's Bag on a wild Pokémon, the game will not reload the graphics on the battle screen, causing a temporary glitch in which part of both the Bag and  screens mix up until the Pokémon catching animation is over, at which point the game will show the battle screen being reloaded.

Present damage
In, the move has a damage formula of its own. This causes the level,, and variables of the regular damage formula to be replaced. Thus, the move deals unusually large or small amounts of damage, depending on the. Additionally, Present calculates type-effectiveness twice, which causes Present to only inflict a quarter of the normal damage against Rock-type and Steel-type Pokémon.

In, both bugs were fixed for regular battles by having Present use the standard damage formula. The old formula from Gold and Silver is still used during link battles to preserve backwards compatibility. This was fixed entirely in Pokémon Stadium 2.

Pursuit-Revival glitch
In Gold, Silver, Crystal, using a Revive, Max Revive or Rare Candy on a Pokémon that fainted from after a switch will revive the Pokémon with the status it had before fainting (Burn, Paralysis, Poison or Sleep). This applies both to healing in and healing outside of battle.

Shiny Transform switch
If a ed Pokémon defeats a Trainer's Pokémon and the player switches it out to a Shiny Pokémon when prompted to, the transformed Pokémon will have a Shiny palette while being switched. This does not happen if player switches Pokémon normally.

Stat rollover glitch
If a Pokémon's effective stat would exceed 1024, the Pokémon's stat is decreased by 1024 (for a minimum stat of 1) during damage calculation only. While most methods to increase stats cap at 999, the Thick Club, Light Ball, and Metal Powder do not.

While it is possible for this to occur for all of these items, this most readily occurs with Marowak (since and  require stat boosts to be received via  for this to occur). If a with an  stat equal or higher than 256 uses  while holding a Thick Club, its Attack will be reduced by 1024 (minimum 1) during damage calculation only.

During damage calculation, if the attacker's (Special) Attack or the defender's (Special) Defense is higher than 255, both are temporarily divided by 4, then (regardless of whether the stats were quartered) both the attacker's (Special) Attack stat and the defender's (Special) Defense stat are taken 256. Thus, stats that are greater than or equal to 1024 (256×4) will be treated incorrectly.

In, this bug was fixed for regular battles but still occurs during link battles to preserve backwards compatibility. This was fixed entirely in Pokémon Stadium 2.

Trainer Counter/Mirror Coat damage
In s only, if the player uses a healing item or a Poké Ball during the same turn as the opponent's  or, their damage will be of at least 4 , twice the minimum standard damage for neutral moves (2 HP).

Shiny Ditto DV manipulation
In Generation I, if a uses the move  while already transformed, it will retain the s of the Pokémon it transformed into after being. Due to being determined by DVs in Generation II, this allows the player to make a  Ditto Shiny by having it use Transform while already transformed; accomplishing this is possible by either having a Shiny Pokémon that knows Transform (, certain glitch Pokémon, or another Ditto) or by teaching a Shiny Pokémon the move, then having the wild Ditto use Mimic on the move Transform. The end result is that the Ditto will be Shiny in the Generation II game.

Trade evolution learnset
that can be taught. This can be achieved by trading such from a Generation I game to a Generation II game at a level where its evolved form will learn a move not present in Generation I. Trading the Pokémon back to the Generation I game will cause the move to become a glitch move.

For example, trading a level 34 from  to  will cause the Graveler to evolve into. Since it is at level 34, it will learn in Gold. If it is then traded back to Red, it will still have the move but the game won't recognize it properly since it is a, so it will become.

Interregional Teleport quirk
If the player travels to either Kanto or Johto in the S.S. Aqua and then s, he or she will be taken to either the or  Pokémon Center as opposed to the last Pokémon Center they used in either region. This does not occur with the Magnet Train. If the player loses a during their trip, they will be sent to their cabin instead.

Legendary beast cry distortion
When the player checks 's Pokédex entry, plays its cry, and then immediately switches to either 's or 's entries, their cry will be distorted.

Stadium 2
fixed the following bugs from :


 * Dragon Fang effect
 * Present damage
 * Stat rollover glitch

Infinite continues
This occurs with any Stadium Cup. If there is a previously suspended game and the player is playing a Stadium Cup, suspending the game after a loss causes a warning message to pop up, telling the player that there is already a suspended game. If "Continue without Suspending" is selected, a rematch with the opponent who just defeated the player will be triggered, but no continue will be used.

Pokédex data localization
Due to a localization oversight, using the Transfer Pak with the English versions of and  and looking up the locations of wild Pokémon in the Pokédex will instead load the corresponding data for the Japanese version.