Master code:
Press Up(2), Down(2), Left, Right, Left, Right, A, B, Start(2) at the main menu. A message will confirm correct code entry.

One hit kills:
Press Up(2), Down(2), X, Y, Y, X at the main menu. A message will confirm correct code entry. Repeat the code for slow deaths.

Toggle unlimited supers:
Press Up(2), Down(2), A, X, A, X at the main menu. A message will confirm correct code entry.

Toggle AI:
Press Up(2), Down(2), A(2), B(2), X(2), Y(2) at the main menu. A message will confirm correct code entry.

Fight as Bastion:
Successfully complete the game story mode as Magneto without losing any matches to face Bastion. Defeat Bastion to unlock him as a selectable character.

Fight as Bishop:
Successfully complete the game in arcade mode as Gambit to unlock Bishop as a selectable character.

Fight as Blob:
Successfully complete the game in arcade mode as Bishop to unlock Blob as a selectable character.

Fight as Psylocke:
Successfully complete the game in arcade mode as Betsy to unlock Psylocke as a selectable character.

Fight as Dark Phoenix:
Successfully complete the game in arcade mode as Phoenix to unlock Dark Phoenix as a selectable character. Alternately, successfully complete the game in story mode as Magneto.

Fight as Sentinel A:
Successfully complete the game in arcade mode as Cyclops.

Fight as Sentinel B:
Win twenty matches in survival mode.

Third costume:
Successfully complete the game in story mode to unlock that character's third costume.

Fourth costume:
Win twenty matches in survival mode with all characters.

Fifth costume:
Successfully complete the game in arcade mode under the hard difficulty setting with all characters.

Sixth costume:
Defeat all ten fighters in time attack mode in under fifteen minutes to unlock the sixth costume for the fighter you selected.

Seventh costume:
Select team mode and choose to fight with eight characters. Defeat all of the your opponent's team by using two or less of your own fighters to unlock the seventh costume for the character(s) you used.

Wolverine gets his original yellow/blue/black costume.
Phoenix gets a red/gold costume similar to Dark Phoenix.
Juggernaut, Gambit, and Psylocke get a costume similar to their comic book original.
Beast gets a blue costume with a yellow X on his chest, and he also has a helmet.

When you chose the seventh costume for Cyclops, Wolverine, Betsy, Juggernaut, Sentinel A (Sentinel), Gambit, Storm, Sabretooth, Rogue and Magneto, they will most commonly appear in their costumes if they were in a "Vs." series game (Marvel vs. Capcom: Clash Of The Superheroes, X-Men vs. Street Fighter, X-Men Children Of The Atom, Marvel Super Heroes vs. Street Fighter).

Eighth costume:
Win forty matches in survival mode as any character.

Ending sequences:
There are three possible endings in the game in story mode.

Regular ending (Magneto's Victory): Defeat Bastion as Magneto.

Alternate ending (Phoenix's Victory): Lose the Magneto vs. Bastion fight and you will go to the Phoenix vs. Bastion fight. Defeat Bastion as Phoenix.

Secret Ending (Fury of Dark Phoenix): Get a "Perfect" victory in the Phoenix vs. Bastion fight. This will also, unlock Dark Phoenix as a playable character.