List of battle glitches in Generation II

:For other glitches in this generation, see List of glitches in Generation II
This is a list of Pokémon battle glitches in Generation II games.
==Pokémon Gold, Silver, and Crystal==
===Beat Up desynchronization===
This can happen when is used in a link battle. Normally, Beat Up does not allow Pokémon with a non-volatile status condition to participate in the attack, but an error in the game's code prevents it from working as intended on the side that used Beat Up.
If the Pokémon with a non-volatile status condition has such an amount of remaining HP that this value 256 corresponds to the index of the Pokémon that used Beat Up (between 0 and 5), the side that used Beat Up will have the Pokémon with a status condition also participate in the attack, causing desynchronization and potentially other glitches as the battle goes on. The opposing side handles the move correctly.
===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.
====Fast Ball oversight====
The Fast Ball 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 .https://www.dragonflycave.com/mechanics/gen-ii-capturing additionally, the Fast Ball has no boosted success rate on Raikou, Entei, and Suicune (when roaming), which it was likely intended to do.
====Love Ball oversight====
The Love Ball only gains a catch rate of 8× on of the same gender and species as the player's Pokémon, rather than on Pokémon of the opposite gender.
====Moon Ball oversight====
The Moon Ball is technically able to gain a 4× catch rate modifier, but the exact circumstances are impossible in normal gameplay.
In the game data, each Pokémon evolution is stored as three bytes: the method of Evolution, an additional parameter, and the evolved species. For instance, evolves by Moon Stone into , which is stored as 0x020824: namely, 02 is the method of evolution by item, 08 is the index number of the Moon Stone, and 24 (hexadecimal version of the National Pokédex number #036) is the index number of . In the case of a Pokémon with branched Evolutions, those evolutions are placed next to each other. After all the evolutions of a given Pokémon, there is a terminator byte with the value 0x00. If a Pokémon does not evolve, there is simply no evolution data for it but the byte with the value 0x00 is still present as usual (this being the first byte for a Pokémon with no evolutions, it is located where the method of evolution would be).
At first, the Moon Ball checks if the wild Pokémon is able to evolve by any item, and then it is supposed to determine if the item used is specifically the Moon Stone. However, it checks for the Burn Heal item instead because it has the index number 0x0A, which in the previous generation was the same index number used by the Moon Stone.
Instead of checking for the Evolution item next to the method of evolution, the Moon Ball incorrectly attempts to check for the Burn Heal item three bytes after the method of evolution. This is the next byte after the evolved Pokémon, which contains the method of the next branched Evolution or the 0x00 terminator byte. The index number 0x0A would refer to the 10th evolution method. However, there are only five programmed methods of Evolution.
Therefore, the Moon Ball applies a 4× catch rate modifier for a Pokémon with at least two branched Evolutions: the first branch must be an evolution by item, and the second branch must be an evolution by a specific method that does not exist in-game.
If the wild Pokémon is into another species, the Moon Ball still checks only how the original species evolves, not the transformed species (although the catch rate modifier is still impossible to obtain nonetheless).
===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.
===Dude glitches===
If the Dude is prompted to show the tutorial of catching Pokémon when the player has a full box, the game will glitch. Effects vary based on the language/version of the game, with the effects in Gold/Silver being more minor (in the English version it is possible to briefly see a HUD with a Level 0 male ?????, but not freeze the game), except in Korean Gold/Silver which may cause a post-battle sprite misalignment glitch without a freeze. Since the dude won't show the tutorial after the player has caught a Pokémon, but the event will activate when the player walks on a specific tile on Route 29, the way to perform this glitch is the following:
#Start a new game and advance until Silver battles the player for the first time.
#Heal in the Cherrygrove's Pokémon Center.
#Poison the player's first partner Pokémon. The way to poison it varies depending of the game: either the player can encounter a Spinarak during the night or a Weedle during the morning in Route 30, and let it poison the first partner.
#Deliver the Egg to Elm.
#Walk either inside the lab or in New Bark Town until the first partner Pokémon faints and the player is teleported to Cherrygrove City, effectively skipping the catching tutorial.
#Fill up the box in the PC.
#Return to Route 29 and walk as if going to New Bark Town.
#In the edge, the Dude will be prompted to show the player the catching tutorial; accept the tutorial.
#The game will glitch when the Dude selects a Poké Ball.
The dude money glitch only occurs in the German version of .
===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. This is possible with an outsider Pokémon holding a Lucky Egg used at the Trainer House. The lowest opponent 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, sets instead 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).
===Menu scrolling oversight===
A flag (bit 0 of memory address FFAC) in memory determines whether options can be scrolled through by holding a direction on the d-pad rather than simply pressing it, which is used by menus such as the bag. This flag is normally unset after closing the menu, and is not usually set in battle menus, meaning the player must tap through battle move menus instead of holding a direction.
Watching the staff credits after defeating keeps the bit set, allowing the battle options to be scrolled through. This effect is cleared however after resetting the game and reloading the save, which is probably a reason why the glitch does not work with credits triggered by entering the Hall of Fame (which resets the game afterwards).
===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 Nightmare (even after waking up from sleep). However, it will be cured of confusion.
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 Park Ball is used from the Ball pocket of the '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.
This glitch happens because the Park Ball is not intended to be used from the Bag, so it isn't programmed to switch into the battle screen when it is used in this way. 
===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===
Using a Revive, Max Revive or Rare Candy on a Pokémon that fainted from after a switch will revive the Pokémon with the non-volatile status it had before fainting. This applies both to healing inside and outside of battle.
===Rival's lowered individual values===
:See also: List of NPC's Pokémon's DVs in Generation II
The rival has a team with lowered individual values (also known as DVs or IVs) in later battles due to an oversight. Specifically, Silver is stored in the game data as two separate characters, each with his own battle sprite:
* Silver uses Pokémon with 13 DVs for Attack, Defense, Special, and Speed during his battles in Cherrygrove City, Azalea Town, Burned Tower, Goldenrod Underground, and .
* Silver uses Pokémon with 9 DVs for Attack, and 8 DVs for Defense, Special, and Speed during his battles in Mt. Moon and Indigo Plateau.
For comparison, all NPC's Pokémon from Generation I also had exactly 9/8/8/8 DVs. In Generation II, each NPC Trainer has their own set of DVs shared by their Pokémon, but several of those Trainers (including multiple Trainer classes) still have 9/8/8/8 DVs like before.
===Sandstorm Spikes glitch===
This glitch occurs with a Pokémon in a which faints, when there are active against the player's Pokémon. Sending out three more Pokémon in succession which will immediately faint from the Spikes, can result in the last Pokémon surviving but with 0 HP. The player can then proceed to escape the battle (i.e. with a successful catch), and every Pokémon will remain in the party with 0 HP. White outs may not occur.
This glitch leads to other derivative sub-glitches, such as the previously known 'instant victory' effect (also used by "any%" speedrunners in the past with arbitrary code execution or bad cloning); in which entering any battle causes it to end (of the partial sort; the battle ends before the Pokémon is sent out rather than the start of the battle itself), effectively allowing the player to always win.
===SRAM clear errors===
An internal function in the code for wiping the save file known unofficially as "ClearWRAM" does not function correctly.List of glitches relevant to the engine It may be worth noting, there are more specific glitches in the game, such as "Hall of Fame SRAM glitch" (box 2+ data becomes invalid, and allows the player to ultimately obtain glitch Pokémon and ????? without bad cloning, if the player clears the save file and enters the Hall of Fame without saving in between). This glitch is loosely similar to Generation I SRAM glitches related to impartial clearing, such as the "ghost Bicycle" phenomenon, "save abuse" and string names leftover from the previous save file with - (move). Another SRAM glitch is the Japanese Poké Communications Center SRAM glitch (mentioned at the header Pokémon Communication Center, though that one is related to exhausted or broken save batteries).
===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 of at least 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).
===Transform glitches===
==Pokémon Gold and Silver==
===Encore-Disobedience===
This glitch involves the move and an outsider Pokémon. If the outsider Pokémon is locked in to a move under Encore, it may still disobey the player. While under Encore, a game freeze or glitch dimension can occur after the Pokémon disobeys the player.
===Present text overflow===
If is used by the 's Pokémon on a Pokémon with 8 or more characters in its name, e.g. , and the game tries to heal the foe, but fails due to them having full HP, the “n't” will appear between the first and second lines. Result:
===Trainer House===
==Pokémon Crystal==
===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.Pokémon Crystal disassembly
===Heavy Ball junk data glitch===
In Crystal, the Heavy Ball's algorithm incorrectly retrieves the weights of , , and , causing them to become junk data that is interpreted as massive weight, giving these Pokémon +40 capture modifier.
==References==
==Related articles==
Category:Glitches by game