High Speed Marathon Mode
     At  the  Title  screen,  hold Z and press B, A, L, L. Now set the
starting speed in marathon mode up to 99.

Bonus Trainers
     At the Trainer Selection screen, hold L + R + Z on controller one
and two.

Mewtwo's Stage
     At the Trainer Selection screen, hold Z and press B, Up, L, B, A,
Start, A, Up, R.

V-Hard Difficulty
     At the Difficulty Selection screen, hold Z and press L, L, A, B.

S-Hard Difficulty
     At the Difficulty Selection screen, hold Z and press R, L, A, B.

Unlock All Selections in Puzzle University
     At the Title screen, hold Z and press A, B, R, A, A, B, R, A.