When you beat the Hercules Cup after it becomes available, you will get Yellow Trinity(Trinity Push). Use "Trinity" on the yellow trinity mark in the lobby to push the huge block and reveal the Keyhole.
It's probably good that you beat Leon first, because he does lots of damage and you need lots of people to fight Yuffie because she moves around too much and is really fast.
You can get Thunder when you beat the Olympus Colisseum once.
Either, go see Merlin, find all 99 dalmations, beat all worlds, or beat all cups at Olympus Coliseum. I meant KH RE: Chain of Memories srry this ain't an answer -gaiga08
You need to beat Olympus Coliseum, Deep jungle, Wonderland and then return to traverse town in order to get the warp gummi which lets you skip any course you have already done.
Kingdom Hearts 1: Beat Cerberus in the hades cup Kingdom hearts 2: Complete the Pride Lands for the second time
Play Kingdom Hearts 2 and wait until Kingdom Hearts 3 comes out. Hope that helps! =D
By attacking her.
You have to beat it alone and within the time limit and then it will let you chose seed
You have to find lots and lots of heartless.
Fight.
You have to beat Ansem
No
Get Kingdom Hearts 2. That's what I did. Or you can try and beat sephiroth and all those extra things.