Hold L1 + R1 and press Triangle(2), Right, Triangle(2), Down, X(2), Left, X(2), Up at the title screen. Release L1 + R1 and a sound will confirm correct code entry. All the boarders will have full stat points.
Mallora Board For Elise
At the main title screen hold L1 + R1 and press, X, Right, Circle, Circle, Down, Triangle, Triangle, Left, Square, Square and Up. A sound will be heard to confirm that it worked. Note: it only affects Elise.
Pipedream course
Win a medal on all Showoff courses.
Play as Mix Master Mike
At the Main title screen, hold L1 + R1 and press X, X, Right, X, X, Down, X, X, Left, X, X, Up. Then select any character.
Rectorator
Enter the following as your name in World Circuit mode, then choose any rider.
Password
Effect
RECOR
Rectorator
Sticky Boards
At the main title screen hold L1 + R1 and press, Square, Square, Right, Triangle, Triangle, Down, Circle, Circle, Left, X, X, Up . A sound will be heard to confirm that it worked.
Unlock everything
At the title screen hold L1 and R1. Now press X Triangle, Right, Circle, Square, Down, Triangle, Sqaure, Left, Circle, X, Down.