Sound test:
To unlock the Sound test option, at the main menu, press Select, A, B, Left, Right, A, Select, Right.
Another World:
To play as the Evil Sorcerer in Another World, beat all “A” levels in puzzle mode. You will receive the code to Another World after beating the final puzzle in level 5-A. Then, at the title screen, press A, Left, Right, A.
Bonus Puzzle sets:
To unlock the final four puzzle sets, get a high score on all default puzzle sets.
Chakkun:
To unlock Chakkun, beat Puzzle Set Z and then complete Puzzle mode in DS Style.