Flagman D.D. mini-game:
Complete the game with a 100% status with all treasure and map pieces. A bonus game can be played after the final level.

In-game reset:
Press Select + Start + A + B during game play.

Instant reset
If you're stuck or just want to reset, press Select, Start, A and B all at the same time. You'll have to start over from your last save point, but you won't lose coins or items.

Unlimited items:
Press Start to pause game play in any stage. Keep pressing Select until a blinking line appears. Hold A + B and press Left or Right to select an item, then press Up or Down to change the amount of that item, up to 99.

Boss battles:
Complete the game with a 100% status with all treasure and map pieces. The levels on the map that have a Boss at the end will have a skull nearby, marked with an arrow. Choose one of these levels. Then hold Down and press A at the level name screen. The game will proceed directly to the Boss.

Secret chapter:
Successfully complete the game. Then, go to the level in which you play basketball against the giant rabbit. Throw an enemy at the wall next to his lair. The wall will break. Throw the enemy again at the next wall to reach a door. Enter the door and you will complete the level unlock a new chapter will be available.

Hidden chapter: [Submitted by:Craig Mitchell]
On the first level when wario is asleep dont press anything and he will snooze along while captain syrup invade his castle and you will hear the finishing sound and you will go into a hidden chapter.