Fight as Akuma
Select 2 Player Vs. mode.
For player one, highlight Spiral, then move to Silver Samuri, Psylocke, Colossus, Iceman, Colossus, Cyclops, Wolverine, Omega Red, Silver Samuri. Wait one second, then press the [Weak Kick] + [Fierce Punch] + [Fierce Kick].
For player two, highlight Storm, then move to Cyclops, Colossus, Iceman, Sentinel, go left to get to Omega Red, Wolverine, Psylocke, Silver Samurai, Spiral. Wait one second and press [Weak Kick] + [Fierce Punch] + [Fierce Kick].
Finally, hold [L] + [R] + [X] + [Y] + [Z] and press [Start] at the continue screen. Alternatively, select versus mode and use the "Quick continue" code to select Akuma.
Fight as Gouki
Enable the "Fight as Akuma" code. Hold [L] + [R] and press [Start] at the stats screen. The name "Gouki" will appear at the bottom of the screen.
Fight as Juggernaut (North American version)
Select Vs. mode and enable the "Fight as Akuma" code. Fight and finish the match, but do not use the "Quick continue" code. Immediately press [Up/Left]x2 at the character selection screen. Juggernaut's face will appear to confirm correct code entry.
Quick continue
Hold [L] + [R] when continuing to keep the same characters.
Marvel Super Heroes screen
Press [Start] + [A] + [C] on the controller two.
Beat up a defeated opponent
After you have defeated your opponent, press [Start] to move and continue fighting.
Hidden options
Pause a fight and press [A] or [C]. A menu that allows controller and sound options to be adjusted will appear.