All Tracks in One-Player Mode:
If you want to have all the tracks in 1 player mode, just start a race then pause the game. While paused, choose OPTIONS/SOUND then go to FX and press L1+L2.

Better Engine in Two-Player Mode:
When you´re about to select a track, press X + Square + Triangle + Circle. A picture of an engine should appear at the bottom of the screen if you are successful.

Invincibility:
This code makes you an invincible skeleton with your full range of energy, magic, bombs and 1-Up's. All you have to do is start the game as normal then pause the game and press L1, L2, L1(3x), L2(3x), Circle, Triangle, Square, Circle, Triangle, Square. You should be an invincible skeleton with full everything. if you don't like being the skeleton then all you have to do is repeat the steps again and you should turn back into the ninja with full everything, but you won't be invincible.

Jumping Bean Cars in Multi-Player Mode:
When you have chosen your vehicles and selected a circuit to race, you can enable this cheat. As soon as the circuit has loaded and the "3, 2, 1 GO" countdown has started, simultaneously press CIrcle and Left.

Race at Night:
When you´re about to select a track, just push L1+L2+R1+R2 to play at night.

Reverse Tracks in Multi-Player Mode:
On the Circuit Selection screen, choose the circuit you wish to race on and press Select. As the cars start to drive into the tunnel, quickly press and hold X and Square. While holding them down, press either Left or Right. If the cheat is successfully activated, the cars will spin around and drive into the tunnel backwards.

Upside-Down Tracks:
When you're about to select a track, press L1 + R1 + X + Down. A sweeping arrow should be drawn at the bottom of the information panel