A Glitch Hell from Lorelei's Elite Four room in English Red/Blue
Out of bounds Glitch Hell (video) is a term for effects of stepping out of bounds on to a 'freeze tile' in the Generation I Pokémon games, most commonly in Japanese Pokémon Red and Green, but also Pokémon Yellow (Japanese) (v1.0 for Yellow) and certain versions of Pokémon Red and Blue on emulators, where the screen doesn't turn white and map corruption occurs, including corruption of the player's sprite in Red/Green. Glitchy sounds may play there. It has not yet been observed in Pokémon Blue (Japanese) or later revisions of Japanese Yellow.
Out of bounds Glitch Hell has not been observed on a real Game Boy running later revisions of Red, Green and Yellow, so it is probably an emulation error. However, the 'real' behavior on the initial revisions is unconfirmed.
Stepping out of bounds can easily be achieved by the tile corruption effect caused by the dokokashira door glitch if in Pallet Town the player steps near the 6th/7th posts from the bottom right and walks around until they can step through them.
In Japanese Yellow (v1.0)
In all revisions of Japanese Yellow, Select glitches do not work, so another walk through walls glitch such as the ledge Safari Zone walk through walls glitch must be used.
When the player steps out of bounds in v1.0 of Japanese Yellow, they may be placed in map D2 (Silph Co. 5F), and an effect similar to entering one of the cycling based glitch maps from English Yellow may occur, where the cycling music plays, the color palette changes after a short period of time, and the player is forced to move while spinning around. The 'low health' beeping may play.
Soon, the player may 'fly' to a Route 10 Glitch City and the palette will be restored. The bird sprite will appear, but the entering a door sound effect will play. After the player enters the Route 10 Glitch City, the cycling music plays and the palette changes again.
If the player is not playing Japanese Yellow on regular Game Boy or Game Boy Color mode, Glitch Hell may not fully start. In Super Game Boy mode, the corruption may begin, but the game may hang with the corrupted graphics unchanged.
In v1.1 (Rev A) and v1.2 (Rev B) of Japanese Yellow, Glitch Hell seemingly does not occur. In these revisions, stepping on a freeze tile may simply overwrite large areas of the memory with '00 39', resulting in effects including the game completely locking up, or a white screen.
'Semi-Glitch Hell' from Japanese Yellow v1.0 in Super Game Boy mode.
Glitch Hell shortly after stepping on a freeze tile.
Glitch Hell after a palette change.
Flying to a Route 10 Glitch City.
A Glitch Hell after stepping into the grass right of Pallet Town in Red/Green.