X-Men: Next Dimension

Computer-controlled fighters stand still
Enter: Up, Up, Down, Down, A, A, B, B, X, X, Y, Y.
(Thanks to trivd@yahoo.com)

Fighters are knocked out after one hit
Enter: Up, Up, Down, Down, X, Y, Y, X.
(Thanks to trivd@yahoo.com)

Unlimited Super
Enter: Up, Up, Down, Down, A, X, A, X.
(Thanks to trivd@yahoo.com)

Unlock bonus characters
Bastion: Beat Story mode with Magneto without losing.
Bishop: Beat Arcade mode with Gambit.
Blob: Beat Arcade mode with Bishop.
Dark Phoenix: Beat Arcade mode with Phoenix or Story mode with Magneto.
Psylocke: Beat Arcade mode with Betsy.
Pyro: Beat Arcade mode with Dark Phoenix.
Sentinel A: Beat Arcade mode with Cyclops.
Sentinel B: Get 20 wins in Survival mode.
(Thanks to trivd@yahoo.com)

Unlock Everything
Enter: Up, Up, Down, Down, Left, Right, Left, Right, A, B, Start, Start.
(Thanks to trivd@yahoo.com)

Unlock New Costumes
Beat Arcade mode with any mutant.
(Thanks to trivd@yahoo.com)