What does altering cave atcually do?

Altering cave is just the same cave as the othere except that the Pokemon living in there are zubats, wild and weak zubats. However if you use and e-reader you can get more Pokemon in that cave.

It does nothing, and no Pokemon either. They were going to put Pokemon in there, like the 1st and second generation but they were going to make firered/leafgreen so they just added some footprints and left it alone, but I think they added zubats to it. But then again zubats are not rare.

It can almost be called useless, until you get an e-reader.

When you get an e-reader, and swipe the special cards, different Pokemon such as houndoor, and mareep will appear in there, there are more different Pokemon, but I can't remember them.

I'm sick and tired of people replying "You can only get Zubats in there." Why do you think they called it ALTERING cave. In case I'm the only one who knows what ALTERING means, it means changing. It's a cave that only has Zubats at first, but if you use an E-Reader, different Pokemon will come. Please rate this.

It only works in Japan, they didn't give us the e-reader cards to make other Pokemon besides Zubats appear for the US version, but that's typical of Pokemon games/Nintendo! They get so much more stuff much more easily in their games in Japan. The only game we got cards for was R/S, and I guess they didn't go over that well, so they didn't bother after those games. When you go into a room where the door at the other end is blocked by boxes or locked, that's where you can (could've) battle "scanned in" trainers and Ultra Rare Berries in R/S with e-reader cards, but they still exist in FR/LG and Emerald, too, as well as Altering Cave, but no cards for us! So, unless you really like Zubats, not much purpose going there.