After you seal the Hollow Bastion, you can fight these guys..
Kurt Zisa- Talk to the magic carpet in Agrabah.
The Phantom- Go to the ships cabin in Neverland and talk to Tinkerbell.
The Ice Titan- Win the Hades Cup and do the Gold Match in the Olympus Coliseum.
Sephiroth- Win the Hades Cup then do the Platinum Match in the Olympus Coliseum.
Win the Hades cup, collect all 99 dalmations, and seal all the keyholes. Then you will unlock the special "Another Side,
Another Story..." video.
Expert Mode Bonuses
After you defeat expert mode, you get your overall stats, a different piece of art in The End screen, and a third background
illustration. You also unlock the secret movie.