Unlockable: Boss Endurance
Finish the game once.
Unlockable: Cake for Collection
Finish the game.
Unlockable: Extra Mode
Collect 120 chests in adventure mode.
Unlockable: Hidden World
Get all the secret map pieces from each of the other worlds. In the tower, you can get any ability bubble, including the Triple Star Rod.
Unlockable: Triple Star
Defeat the boss on area 8.
Unlockable: Fire Sword
Super Electricity:
Find a black cloud. Then use the electricity.
Birthday Message:
Play on your birthday, and you'll get a special message after the startup sequence.
Power Mixer:
Acquire the Sword Scroll and the Bomb Scroll; next, you can use your DS stylus to drag the following ability bubbles on top of one another to make new items
Create Fire Bomb - Fire + Bomb.
Create Fire Sword - Fire + Sword.
Create Ice Bomb - Ice + Bomb.
Create Ice Sword - Ice + Sword.
Create Spark Bomb - Thunder + Bomb.
Create Spark Sword - Thunder + Sword.
Get Ghost Power:
Get all the pieces of the Ghost Medal. Go to where a mini-boss is and defeat the ghost that appears; eat the ghost to power up.
Source: http://www.gamingcheats.com/nds/8111/kirby-squeak-squad-cheats.html
