Dokokashira door glitch
The Doko-Kashira Door Glitch is a Pokémon Red/Green (JP) exclusive glitch which can manipulate the location as of which the next door (or entrance) will take the player to. It is mainly used for Speed Running videos for Pokémon Green as one could force the next door the player enters into taking them into the Hall of Fame.
The glitch no longer exists in non-Japanese versions of Pokémon Red, and Pokémon Blue because it involved the player using the select button to switch Pokemon as well as items; this feature was removed in Pokémon Blue, and non-Japanese versions of Pokémon Red possibly due to the fact that it could affect the game thinking that one is switching a Pokémon and an item.
Method
External Links
[1] pokemonbug.oh.land.to; a japanese Pokémon site translated into English, which has noted the Doko-Kashira Door Glitch as well as the methods involved in it.
[2] pokemonbug.oh.land.to in japanese.