The Altering Cave (Japanese: へんげのどうくつ Changing Cave) is found in
Pokémon FireRed, LeafGreen and Emerald. Only Zubat can be found in
this cave, but it is possible for the Altering Cave's wild Pokémon to
be altered by using Mystery Gift at a Wonder Spot hosted by Nintendo.
Despite this, no country has ever held an event to make use of this