Pac-Man World Rally [cheats]

Black Bomb
Eat five blue ghosts in Pac-Mobile mode to unlock the Black Bomb upgrade for the Green Bomb.

Play as Fygar from Dig Dug
Win the circuit races and rally under the hard difficulty setting.

Play as Pooka from Dig Dug
Win the circuit races and rally under the normal difficulty setting.

Play as The Prince from Katamari Damacy
Win the circuit races and rally under the easy difficulty setting.

Unlock Cups
Nore: Cups will only be unlocked for the difficulty at which you play the required cups to unlock it. (i.e. beating the Watermelon Cup on Normal will only get you the Classic Cup for Normal):

Classic Cup - Complete the Watermelon Cup
Rally Cup - Complete the Classic Cup
Watermelon Cup - Complete the Cherry and Grape Cups

Unlock Nightmare Difficulty Setting
To unlock the Nightmare difficulty setting, complete the Rally Cup on Hard difficulty.