Play as Slim Jim
At the rider selection screen in pro quest mode, press Down(2), Left, Right, Up(2), Y to unlock Slim Jim. Alternately, successfully complete the game with any rider to unlock a bonus bike and Slim Jim.

Play as Amish Boy
Successfully complete the game with Dave Mirra, Ryan Nyquist, Joey Garcia, Troy McMurray, Mike Laird, Chad Kagy, Tim Mirra, Kenan Harkin, Shaun Butler, and Leigh Ramsdell to unlock Amish Boy.

All Bikes
At the bike selection screen in pro quest mode, press Up, Left, Up, Down, Up, Right, Left, Right, Y to unlock all bikes. Note: Each time a new bike is selected this code will have to be re-entered.