Full health
Pause the game and select the "Audio" option at the menu. Then, press R, L, R, L, B(2), X(2), R, X. If you entered the code correctly, a message will appear.

Infinite Electric Bombs
Pause the game and select the "Audio" option at the menu. Then, press R(2), L(2), B(2), X. If you entered the code correctly, a message will appear.

200,000 Klokkies
Pause the game and select the "Audio" option at the menu. Then, press L(2), R(2), B, X, B. If you entered the code correctly, a message will appear.

Alternate ending
Collect all 100 Orbs and successfully complete the game to view an alternate ending.

Faster credits
While viewing the credits, hold R.

Fill Electric Bombs faster
While you are on the vines, hold X.