J. J. Sawyer
Finish the game with an "S" rank in all levels.

Naomi
Finish the Downtown level with a "B" rank.

Oscar
Finish the game with an "A" rank in all levels.

The Insider
Finish the Storage level with a "B" rank.

Stunt attack mode
Finish the game in story mode.

Unlock Everything
Select story mode, then press Up, Down, Up, Down, L1, L2, R2, R1, Select + X at the level selection screen. A sound will confirm that you entered the code correctly. All levels, characters, and bonuses will be unlocked.

New Kat Outfit
Finish score attack mode with high scores in all levels.

New Ethan Outfit
Finish stunt attack mode.

Always on Top of the Score List
Choose New game and enter your name as Ethan and the game will think you've completed the game.