|This article is incomplete. Please feel free to add any missing information about the subject. It is missing: an in-depth explanation, and a short description of the exploits.
The Battle Tower SRAM glitch is a major glitch in Pokémon Crystal that works similarly to the Hall of Fame SRAM glitch in Pokémon Gold and Silver. It is a rare example of a powerful Generation II natural glitch. Notably, the only known (glitched) route for the Crystal any% No Save Corruption speedrun is based on this glitch.
The glitch involves winning a battle at the Battle Tower, then starting a second game, saving the game before the getting the starter, and abusing the "quicksave" feature of the Battle Tower to only load the party data from that save file at the Battle Tower. For this to happen, it is necessary that the player has the same Trainer ID in both games, which makes the glitch very unlikely to happen in casual play, but it can be pulled off with luck manipulation.
This glitch allows the player to have a party of 0 Pokémon in an area that is not supposed to be accessible before the getting the starter, which can trigger the instant victory effect as well as the God Egg glitch, which is useful for obtaining an unterminated name Pokémon (Generation II).
In addition, stored PC Pokémon from the previous save file are carried over. The player can abuse the ????? from God Egg glitch with past stored Pokémon for byte swap glitches. For example, they can generate key items for the duplicate key items glitch and expanded Balls pocket, or store a Pokémon knowing Beat Up/Acid Armor beforehand to obtain Celebi/Mew.
1. Start a new game, manipulating any Trainer ID.
2. Play the game normally until the player reaches the Battle Tower. Win a battle in the Battle Tower.
3. The attendant will heal the player's Pokémon to full health, and ask whether the player want to battle the next opponent ("Next up, opponent no.2. Ready?"). Choose "NO".
4. The attendant will then ask the player "SAVE and end the session?" Choose "YES".
5. The game will reset automatically. (The player may need to hard reset anyway for the upcoming manipulation.)
6. Start another new game, manipulating the same Trainer ID as before. Save the game before getting the starter.
7. Play the game normally, without saving the game again, until the player reaches the Battle Tower. Enter the Battle Tower.
8. If the glitch worked, as soon as the player enters the door, the attendant will ask the player to resume the battle tower challenge. The player will walk to the elevator in a weird way.
9. Lose the battle. The player will leave the Battle Tower with no Pokémon.