Kingdom Hearts: Chain of Memories
Beat the game with Sora.
Mushu's Summon Card:
Can be found in one of the random doors that appear after the Golden Bar card is used.
Reverse Rebirth mode:
Beat the game.
Sora's Ultima Weapon:
For sale at Mog shops after you've beaten Reverse Rebirth mode.
Special thanks to Revolution readers Saito G, Yukikaze, Randy, SteamPunk and Kim!