During a game, activate all the warping mirrors.
Collect 100% of the treasures during a game.
Finish the game with a 100% completion. The "Boss Rush" option will now be unlocked at the main menu.
During a game, find the spray paint to unlock the "Kirby Colors" option in the Treasure list.
Successfully complete the game after defeating the final Bosses. Metaknight's Sword will now appear in front of the Magic Mirror.
During a game, activate all of the portal switches. Then, go to the main hub of of Rainbow Route (Area 1). The Power Center door is located in the top left corner.
Find the CD treasure during the game to unlock the "Sound Test" option in the Treasure list. For more songs, find the Musical Scores during a game.
To find the CD Player, look in Peppermint Castle.
In Candy Constellation where you can see two treasure chests (one big and the other small), the big one contains a heart container.
Unlock all of the mirror pieces to unlock a secret mirror in Area 1.
While you have the sword ability (or Master), go to very shallow water. Press Up + B( or with Master Down + B + Up in that order). As he goes up, he will keeps his snorkel on.
Get the Tornado ability before you get to him. When you reach him, hold B. Kirby will spin and go up. While spinning, keep hitting Kracko. Keep doing this until his life is gone. You can also do this with other Bosses.
When you fight Mr. Frosty, the walrus Boss in Peppermint Palace and Moonlight Mansion, the name above his HP bar reads "Mr. Flosty" with an "L" instead of an "R".