The Hall of Fame SRAM glitch is a major glitch in Pokémon Gold and Silver, including non-English versions of the game (confirmed working on both English and Korean Versions). It is a rare example of a powerful Generation II natural glitch, another example being Coin Case glitch.
It was documented by the Pokémon speedruns community, as well as Sally and Torchickens (video).
The glitch involves defeating the Pokémon League Champion without the player having a save file, and having cleared the save data with the Up+Select+B beforehand.
This causes the game to keep corrupted box data on the save file, allowing for the player to obtain a bad clone.
Obtaining a bad clone
1. The player must first complete the story without saving, with Up+Select+B used to clear the save file beforehand.
2. Use "move PkMn without mail" to move one Pokémon into the top slot of box 2
3. Use it again to bring a second Pokémon to the second slot of box 2
These steps will corrupt the first Pokémon in the box to become a hybrid of the original Pokémon and a ????? (00). The hybrid can be taken into the Day Care and out to become a stable ????? (00), which can be used to set up ????? party overloading and derivative glitches such as Celebi glitch.
Box 2's number of Pokémon counter according to the game may also remain at 0.
This glitch can be used to obtain a held item (including key items, which is useful for the duplicate key items glitch) based on the species of the top Pokémon in the box. For example, Togepi's ID is 0xAF (dec:175), which would give the player the Squirtbottle item.