Unlock everything:
     At  the  main  menu,  hold  Left Trigger then press Right, Right,
Left, Left, Down, Up, X.

Unlock Bonus Characters:
     Beat  arcade  or  story  mode  using  the following characters to
unlock bonus characters:

Unlock:            Beat:
Bastion            Story mode w. Magneto (without losing)
Bishop             Arcade mode w. Gambit
Blob               Arcade mode w. Bishop
Dark Phoenix       Arcade mode w. Phoenix or Story mode w. Magneto
Psylocke           Arcade mode w. Betsy
Pyro               Arcade mode w. Dark Phoenix
Sentinel A         Arcade mode w. Cyclops
Sentinel B         20 wins in Survival mode