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Battling a glitch Trainer
Glitch Trainers are Trainers that can only be battled via the use of glitches.
Glitch Trainers can be battled in one of two ways: the old man glitch (if the player's name contains certain special characters in the 3rd, 5th, or 7th slot) or the Ditto glitch (using Special stats ranging from 201-255RB or 201-253Y).
When battling a glitch Trainer, the music begins as normal wild Pokémon music. Unlike other Trainers, glitch Trainers say nothing before or after the battle, and often use glitch Pokémon.
If the player encounters a glitch Trainer via the old man glitch, the preceding character to the one that caused the battle will be used to determine which team will be used. If the player encounters a glitch Trainer via the Ditto glitch, the "Attack stage" of the Ditto used will be used to determine which team will be used. The Attack stage is how many stages the Ditto's Attack stat has been raised or lowered; 7 is the default, 1 is the lowest possible, and 13 is the highest possible. When encountering Trainers via the old man glitch, only very high team numbers are used due to the fact that the characters that can be put in the player's name all have high index numbers. When encountering Trainers via the mew glitch, unless Ditto's Attack stage is changed, the game will load the 7th team. Most Trainers only have one set team, causing glitchy teams if not encountered via the Ditto glitch and having the Ditto's Attack lowered to stage 1 (since they do not have a 2nd, 3rd, etc. team). The only exceptions are Prof. Oak and the Blue, who have three different teams based on the player's starter Pokémon. This is the only way to face Prof. Oak with his original team.
- Main article: ZZAZZ glitch
If the player performs the Ditto glitch and uses a Special stat of either 251, 252, 254, or 255, the ZZAZZ glitch will be triggered. This glitch changes most in-game bytes to have a value of 153, hence the players name will be changed to consist of multiple amounts of the letter "Z" (index number 153). Most of the player's Pokémon will be changed to level 153 Bulbasaur (index number 153).
- Main article: Trainer House glitch
Glitch Trainers may appear in the Trainer House as a result of the Trainer House glitch.
Glitch-only Trainer classes
this hiker is a unusall hiker: it activates with a code whitch is for gameshark. i found it fooling around with a with the code changing the values to non/glitch pokemon. it only activates in the grass in the place of a wild pokemon battle. the pokemon are being found out now, i think the code is only for pokemon yellow, the code is 01D1D7CF. its pretty random to find this pokemon trainer with only a code.
Prof. Oak can be battled by performing the Ditto glitch with a Special stat of 226, or by performing the old man glitch with the character MN in the third, fifth, or seventh slot of the player's name.
In the Generation I games, there is unused Trainer data for Prof. Oak. This implies that it was originally going to be possible to battle him.
In the data, Oak normally has a level 66 Tauros, a level 67 Exeggutor, a level 68 Arcanine, a level 70 Gyarados, and one of the Kanto starter Pokémon at level 69. This places his strength on-par with Blue, who is the Pokémon Champion and grandson of Professor Oak. Additionally, four of his Pokémon are identical to the ones used by Blue, but are at higher levels, so originally Oak may have been intended to be in the game as the Champion, or at least another high-ranking Trainer, possibly in the same manner as Red in Generation II. This is supported by an email on the PC in Professor Oak's Laboratory, from the Indigo League issuing a challenge to all Trainers and specifically requesting Oak to come visit them.
When battling Prof. Oak via the Mew glitch, the Attack of the wild Ditto must be lowered by 4, 5 or 6 stages for Prof. Oak to have the Charizard team, the Venusaur team or the Blastoise team, respectively.
Professor Oak will always use a glitch team if encountered via the old man glitch. This is because a character with a hexadecimal identifier of 01, 02, or 03 would be required in the player's name for one of these teams, but there are no characters with these hexadecimal identifiers.
Chief (Japanese: シルフのチーフ Sylph's Chief) is an unused beta Trainer class that is found in Generation I. Chief can be battled through the use of the old man glitch when the player's name contains a dash in the third, fifth, or seventh letter slot, via the Ditto glitch with a Special stat of 227. Chief's sprite is the one of a Scientist. The only time the word is said in-game is in Celadon City, by one of the Team Rocket Grunts, perhaps indicating that Chief might have appeared in other places and been able to battle the player. The Japanese name indicates that the player would fight the head of Silph Co. Unlike Prof. Oak, there is no team programmed for Chief.
Jacred is a glitch Trainer class. Its name is derived from the preset names the player chooses for themselves and their rival, such as their names being "Jack" and "Red" will make "Jacred". The only way to fight 'Jacred' is by performing the Ditto glitch with a Special stat of 200. Unlike other glitch Trainers, Jacred has no defined sprite and can instantly crash the game when it is about to send out the first Pokémon.