Nothing.
there is no reason to altering cave. It's something that the designers put in there but didn't have any time to do anything to it.
it is the fossil you didn't get in the desert
Altering cave is on 5 or 6 island.
There is no Altering Cave in Pokémon Platinum.
You can't do anything with altering cave unless you have an E Reader.
There are no moveable rocks in Altering Cave.
It's normally no pokémons in the altering cave i heard that you must do something ;)
Altering cave does not change into traveler's cave. Altering cave can only offer new Pokemon (since all it offers are zubat) after using Mystery Gift.
Altering Cave in Pokémon FireRed on Six Island is a special cave that typically only has wild Zubat within it however during a Nintendo-sponsored event, Nintendo would be able to send you a download via the Mystery Gift feature that would change the wild Pokémon that appear in the Altering Cave. Pokémon that are capable of appearing in the Altering Cave via the Mystery Gift download are Mareep, Aipom, Shuckle, Pineco, Smeargle, Stantler, Houndour and Teddiursa however there is no way to change the Pokémon appearing in the Altering Caves due to Nintendo no longer releasing distributions for Pokémon FireRed.
No.
Only zubat can be found in Altering Cave. Altering Cave was a location intended to be used for an event where Mystery Gifts could change the pokemon encountered in the cave, but these Mystery Gifts were never officially distributed.