Nothing but Zubat.
Zubat.
altering cave,
You can catch a Houndour in the Altering Cave in Pokemon FireRed.
The only Pokemon you can catch is Zubat.(talk about a let down)
Probably.
There is no altering cave in pookemon red since the sevii islands don't exist in Pokemon red only in Pokemon firered and leafgreen in six island after going past the forest and the altering cave is also in Pokemon emerald in route 103 a cave appears after beating the elite 4.
It is a mysterious cave filled with Zubat. If you did something with the Mystery Gift and a Wonder Spot, there would be 8 different Pokemon found there, but Nintendo hasn't yet done anything with it. In summary, it's useless (unless you need a Zubat).
You can't do anything with altering cave unless you have an E Reader.
Absolutely nothing.
Nothing.
Zubat can be encountered in the Altering Cave. Originally, there was going to be a set Mystery Gifts distributed which could change which pokemon were encountered in the Altering Cave, but the Mystery Gifts were never distributed.
Six island its in the north.