Altering Cave...a Cave on Island 6, that has many Pokémon Trainers Puzzled. It has nothing in it except Wild Zubats...but when delving into the coding, it seems to have many more Pokémon. Here is a List of those Pokémon
For all we know, it could have more such as legendaries, but as far as we know it just has the above Pokémon, which, apart from Zubat are not found anywhere else in the game.
It seems to change them it requires something done in the Mystery Gift function of the game. We'll bring more details as soon as possible