To get all characters and all tracks, first set a record. After that type your name "no time" then go to the main menu. Hold L1, L2, R1, R2 then press right, left, right, left, circle, square, circle, square then youll have all tracks and all characters.
Get Mawhonic
Just beat the last of the first four circuits in tournament mode.
Hard Mode Cheat
Go to the main menu and hold "L1+L2+R1+R2" and while holding press Triangle and you will hear a noise. "Hard Mode cheat on" will flash. Do the same to turn it off.
Repairs
During a race when you have damage Hold L2 + R2 to repair with no loss of speed.
Unlock Sebulba
To unlock Sebulba play as Anakin in tournament mode win every track in first place.
Unlock Sebulba episode 1
To unlock Sebulba episode1 pod play as Selbulba in tournament mode and finish every race in first place.