At first only Zubat are found there, but using Mystery Gift with other players unlocks:
Mareep
Aipom
Pineco
Shuckle
Teddiursa
Houndour
Stantler
Smeargle
Altering cave is on 5 or 6 island.
There are no moveable rocks in Altering Cave.
It's normally no pokémons in the altering cave i heard that you must do something ;)
Only zubats =)
Catch zubat but that's it.
You can catch a Houndour in the Altering Cave in Pokemon FireRed.
as i recall you can only find zubat in altering cave but after you do some certain event then you can find other Pokemon like teddiursa
it's on one of the three islands
Catch some zubat :P.
you use a ultra ball
try going to Altering Cave. sometimes there are Houndour there.
you can get hound[or in altering caVE AND EVOLVE IT