Level Warp
In Level 4: Wizards and Lizards, as soon as you hit the stop watch to start the time trial, hit select. This will warp you to the end of the level.
Unlock the "Real" Ending
Get all 46 gems to get the real ending.
Unlimited Lives
When you die click the start button, then highlight the word Warp Room and press A.
All Levels
Click new game, put in Wombat for the name, and all levels will be unlocked.
Defeating Wa Wa
When you are facing Wa Wa, crunch will shoot things at you. He will fire blue beams that you should jump over. When he fires green things, duck. Hop from one panel to another. When you reach Crunch quickly spin. Watch out -- the panels will sink. Try to get a head start on each run. Once Crunch jumps back at the beginning, run. When you spin him the next two times, do not stop running.
Defeating Ro-Ko
Roll around the side of the area without going in the center. Every rock will come near you, and Crunch will mostly miss you.
Defeating Lo-Lo
Watch where the mask floats and shoot there.
Defeating Py-Ro
Hold B to charge the water cannon or you will never hit.
Defeating Crunch Time
Every time freezeballs, beams, or fire comes out, jump over the fence into the inside platform. They cannot touch you there, but fireballs will land everywhere -- just watch for their shadows. There is a series of elements you have to avoid. Then shoot Crunch with the bazooka and spin Cortex. The series is: fireballs, shoot Crunch, spin Cortex, freezeballs, fireballs, shoot Crunch, spin Cortex, fire, fireballs, freezeballs, fire, shoot Crunch, spin Cortex, beams, fireballs, fire, beams, freezballs, fireballs, beams, shoot Crunch, spin Cortex. If you win, you will unlock five secret levels for which you must collect a certain amount of relics in order to open the doors.