Here is the full list of all 12 Castle of Illusion Starring Mickey Mouse achievements worth 400 gamerscore.
Found all the Magic Diamonds.
Completed all Castle Statues.
Collected all of Donald's Chili Peppers.
Defeated Mizrabel and rescued Minnie.
Found 50% of all Magic Diamonds.
Collected all the Magic Playing Cards.
Bounced on 7 enemies in a row without touching the ground
Completed a stage in Time Attack mode.
Completed a Castle Statue.
Broke the illusion of 25 enemies with projectiles.
Broke the illusion of 75 enemies.
Unlocked a Castle Painting.