Okay Aeris is dead from the end of disc 1 and on. She can't be revived no matter what you do. If she did it would change the ending and there is only one ending. People keep saying that but they have no proof at all. Oh yeah dont forget that you cant play as sephiroth or young cloud either..
If you really wanted to, you could you gameshark to change sprites, but it really doesn't do any thing but make the game crash.