Upon completing the game, or at least once you can enter the End Of The World you can access Kurt Zisa as an optional boss in Agrabah. To reach the boss, return to Agrabah; from there go to Aladin's house and speak with him. When you wish to fight him, go to the outside of th Bazzar and the Magic Carpet will be waiting for you. Use the carpet and it will take you to the desert, were you will encounter Kurt Zisa. Make sure you understand his weakness to Fire, Make sure you use Firaga and Mushu. Also, have a high resevoir of MP at your disposal.