In the main menu of the game, go to the "Extra" section and enter the following cheat codes:
YCMWKP -Baseball player
CQSZBJ - Classic alien
HVGTPG - Natalia Kowalski in disguise
XKGZVJ - Gorilla Outfit
3D74QF9 or 3GCC7XR or N7NN4F9 - High speed during bonus pursuit missions (use the terminal outside the police station)
MRPHVQ - Karate kid
SSVKCT - Minotaur
FHSZYG - Ninja
NRRXYM - Pharaoh
CNCNRH - Pop star
MHHRHM - Race car driver
WRSKVC - Roman soldier
RJYZHC - Samurai Warrior
SYFMWJ - Football player
DWJVCT - Chan's Drakonas car
VZHHDM - Car Relocator
GYSTQP - Werewolf