X-Men: Mutant Academy 2 [PSX]

Battle against Spider-Man
To play against Spider-Man, you must use Wolverine in Arcade mode, and have all perfect matches. After about half way through, after you take down your forth or fifth opponent, you will get a battle screen that says Wolverine vs. Spider-Man.

Master code:
Press Select, Down, R2, L1, R1, L2 at the main title screen. All features, including alternate costumes, outro FMV sequences, behind the scenes movie pictures, the Pool Party, and Psylocke, Juggernaut, Spider-Man, and Professor X will be unlocked. To use Spider-Man, highlight Cyclops and hold L1 at the character selection screen. To use Professor X, highlight Magneto and hold L1 at the character selection screen.

Juggernaut:
Successfully complete the game using all default characters and Psylocke in arcade mode.

Professor Xavier:
Successfully complete the game as Juggernaut. Then, highlight Magneto and hold L1 at the character selection screen.

Spider-Man:
Fight in arcade mode until you face Spider-Man. Defeat him and finish arcade mode. Then, highlight Cyclops and hold L1 at the character selection screen.

Psylocke:
Successfully complete the game as Wolverine in arcade mode.

Alternate Costumes
Just beat Xavier's training mode with any character. You will open up a new costume for that character.

Psylocke's 4th Outfit (The Shadow)
Play Survival Mode and get 20 wins with at least 10 perfects while using Psylocke. According to Galford's FAQ, he said it worked for 5 perfects, but I did it with 10 perfects.

Unlock Everything...
At the start screen, PRESS:
select, down, R2, L1, R1, L2.

To select Spider-Man, highlight Cyclops and hold L1.

To select Professor X highlight Magneto and hold L1