Alternate Costumes:
On any character hold Up or Down for three seconds. If the character you want is on the top row, hold UP. If they're on the bottom row, hold DOWN.

Play as Anita:
Note: This code may only work on the Japanese Version of this game.

Finish the game and save to the Memory Card. Load the Memory Card then do the Thanos code in Arcade mode. Quit, then do the Dr.Doom code in Arcade mode. Quit then go to Arcade mode. Make sure the cursor is on Spiderman then do the following: Up, Right, Down, Left, Up, Right, Down, Left, press and hold Up then press and hold Jab, Strong, then Fierce. This will select Anita.

Play as Dr. Doom:
To play as Dr. Doom, do the following:

Beat the game on any difficulty level (you can continue as much as you want).

Select Arcade Mode

Make sure the cursor is on Spiderman (Captain America for Player 2)

Press Down twice (holding down the second time), then immediately press and hold weak kick, then (while continuing to hold weak kick) press and hold medium kick, then (while continuing to hold weak kick & medium kick), press and hold strong kick. The code must be done rather quickly so it may take some practice.

Dr. Doom's special moves are:
Energy Beam: QCF + P
Photon Shot: HCB + P
Rock Shield: HCB + K
Photon Array (Infinity Move): QCF + All Punches

Play as Thanos:
To play as Thanos, do the following:

Beat the game on any difficulty level (you can continue as much as you want).

Select Arcade Mode

Make sure the cursor is on Spiderman (Captain America for Player 2)

Press Up twice (holding up the second time), then immediately press & hold strong punch, then (while continuing to hold strong punch) press and hold medium punch, then (while continuing to hold strong punch & medium punch) press and hold weak punch.

Thanos's special moves are:
Charge: HCF + P 9can be done in the air)
Rock Throw: HCB + K
Bubble Throw: HCF + K
Infinity Gauntlet (Infinity Move): QCB, QCB + Any Button (each button gives a different gem move)

Smashing Pumpkins:
When you use a reality gem, press SELECT and your character will throw out pumpkins!

Taunt:
While playing, press Down, Down, Select to taunt your opponent.