Enter code at Main Menu: D-pad Up, D-pad Down, D-pad Left, D-pad Right, Square, R1, Triangle, L1.
Christ Air
Do a Backwards Grab then press Circle.
Coffin
Do a Double Grab then press Circle.
Danny Way's Mega Park
There's an unlockable skate park in the game called Danny Way's Mega Park. To unlock it, you must advance through all video and photo shoots that are relevant to achieving full sponsorship. Full sponsorship entails board, truck, and wheel sponsorship.
After you achieve full sponsorship status, you will receive an invitation to Danny Way's Mega Park. You'll need to compete there - and win - in order for it to be fully unlocked to use at any time.
Dem Bones
You can unlock a hidden character called Dem Bones by breaking each bone in your current character's body three times. Check the injury log to peek at your progress.
Frontflip
Grab and move the Left Analog-stick Down or Up.
Plan B Warehouse
To unlock the Plan B Warehouse, beat Ryan Gallant's pro challenge.
Rocket Air
Hold L2 + R2 + Right Analog-stick Down.
Unlock All Characters
At the main menu, press L1, L2, R1, R2, Down(2), Square, Triangle to unlock all characters in Free Play and Party Play mode. If you entered the code correctly, a message will appear.