Infinite Lives Trick
To get an extra life, get the star at the beginning. Press Start and select "Try Again". Go to the same level and go back to get the star again. Repeat this as many times as needed to collect an unlimited number of lives.
Unlock Higher Mini-Game Difficulties
To access the higher difficulty settings for the mini-games, you must beat the difficulty setting before it. In the beginning, beat the Easy setting to unlock the Normal level. Beat the Normal level to open the Hard level. Then, beat the Hard level to access the Intense difficulty level.
Boss Battle & Movie Viewer Modes (bonus) modes
Collect all crystals in the game (it will say 100% on your file at the file selection screen) to unlock Boss Battle (Bosubuchi) and Movie Viewer (Zenbu Miseru) modes.
Break the Walls
There are various walls that must be broken by specific abilities. The ability depends on the color of the wall:
Light Brown: Spike
Brown: Rock
Red: Fire
Green: Cutter
Black: Bomb
Blue: Ice