The Altering Cave is a strange landmark on Outcast Island in the Sevii Islands, seemingly serving no purpose other than as an empty cave at the back of a long water route. This cave was meant to be used to collect data from Wonder Spots, which would "alter" the wild Pokemon found inside. However, this never came to fruition outside of Japan and the cave remained as a hole in the wall with no special attributes.

These are the Pokemon that were to have been distributed at the cave...but keep in mind there is no way to catch these Pokemon there and that this is just a list for completion's sake: