All Levels Characters and Secrets:-  At the story mode screen press (where you can choose the levels) Up, Down, Up, Down, L1, L2, R2, R1, Select + X when you enter the code correct you wil hear a grind sound. 

J. J. Sawyer:-  Successfully complete the game with an "S" rank in all levels.
 
Naomi:-  Successfully complete the Downtown level with a "B" rank.

Oscar:-  Successfully complete the game with an "A" rank in all levels.

The Insider:-  Successfully complete the Storage level with a "B" rank.

Stunt attack mode:-  Successfully complete the game in story mode.

Alternate costumes:-  Complete one of the following tasks to unlock a third costume for the indicated character.

Ethan:-   Successfully complete stunt attack mode.

Kat:-   Successfully complete score attack mode with high scores in all levels. 

Level select:  Press Start to pause game play, then press Square, Circle, Triangle Square, Square, Circle, Start.

Invincibility:  Press Start to pause game play, then press Square, Circle, Triangle X, Square, Circle, Start.

Pass through objects:  Press Start to pause game play, then press Square, Circle, Square Circle, Square, Circle, Start.

Corporate HQ: Stop on cable car:  Select Ethan and enter stunt mode. Play the Corporate HQ level and go to the last cable car. When grinding it, press R1 and you will stop on it.

Fall through door:  Unlock Naomi, select freestyle mode and go to level three (Industrial). At the end of the level, go off the left ramp from the exit (at the search lights). Avoid the big pipes, use Speed and Boost Jump, and you should fall through the door and float in darkness.

Stuck on wall (demo version):  In the first level near the pile of boxes out the back of the Chinese shop, go up the wall and land on the wall. You will not fall down and can as many stunts as desired. You can stay there and do stunts up to and after the time has stopped.

GameShark Codes:

Must Be On 0E3C7DF21645EBB3  0C1A6183F88DDC7F
Inf Boost 2C27A5A9F8FC3F7E
Super Score 2C27A6A1F8FC02BC
Inf Time 3C2A3E97BBFCFEFE
Enable Downtown 3C29B287F8FCFEF1
Hideaway Low Time 3C29B28BF8FCFEFE
Hideaway 0 Falls 2C29B28FF8FCFEFE
Hideaway 99 Best Combo 2C29B293F8FCFE53
Hideaway Super Score 3C29B2974C3EC03A
Hideaway Grade A 2C29B29BF8FCFEF1
Enable Industrial Level 3C29B29FF8FCFEF1
Downtown Low Time 3C29B2A3F8FCFEFE
Downtown 0 Falls 2C29B2A7F8FCFEFE
Downtown 99 Best Combo 2C29B2ABF8FCFE53
Downtown Super Score 3C29B2AF4C3EC03A
Downtown Grade A 2C29B2B3F8FCFEF1
Enable Storage Level 2C29B2B7F8FCFEF1
Industrial Low Time 3C29B2BBF8FCFEFE
Industrial 0 Falls 2C29B2BFF8FCFEFE
Industrial 99 Best Combo 2C29B2C3F8FCFE53
Industrial Super Score 3C29B2C74C3EC03A
Industrial Grade A 2C29B2CBF8FCFEF1
Enable Corporate HQ 2C29B3CFF8FCFEF1
Storage Low Time 3C29B3D3F8FCFEFE
Storage 0 Falls 2C29B3D7F8FCFEFE
Storage 99 Best Combo 2C29B3DBF8FCFE53
Storage Super Score 3C29B3DF4C3EC03A
Storage Grade A 2C29B3E3F8FCFEF1
Enable Penthouse 2C29B3E7F8FCFEF1
Corporate HQ Low Time 3C29B3EBF8FCFEFE
Corporate HQ 0 Falls 2C29B3EFF8FCFEFE
Corporate HQ 99 Best Combo 2C29B3F3F8FCFE53
Corporate HQ Super Score 3C29B3F74C3EC03A
Corporate HQ Grade A 2C29B3FBF8FCFEF1
Penthouse HQ Low Time 3C29B303F8FCFEFE
Penthouse HQ 0 Falls 2C29B307F8FCFEFE
Penthouse HQ 99 Best Combo 2C29B30BF8FCFE53
Penthouse HQ Super Score 3C29B30F4C3EC03A
Penthouse HQ Grade A 2C29B313F8FCFEF1