To unlock the cheat menu, type SPAM at the Configuration menu, a submenu of the Options menu.
To fight as Akuma, highlight Spiral at the character selection screen for three seconds. Then move to the following characters without stopping: Silver Samurai, Psyloke, Colossus, Iceman, Colossus, Cyclops, Wolverine, Omega Red, Silver Samurai. Wait three seconds on Silver Samurai before pressing short kick + fierce punch + roundhouse.
To fight as Juggernaut, you must first activate the cheat menu(Type SPAM at the Configuration menu). Then, during the game hold all three punch buttons.
To fight as Magneto, you must first activate the cheat menu(Type SPAM at the Configuration menu). Then, during the game hold all three kick buttons.
Type god at the message screen. The phrase "God mode enabled" will appear. Exit the message screen. The phrase "Sinister has changed the cheat code" will appear at the top left portion of the screen. In this mode, fighters will receive greater damage.
Enable cheat mode and begin game play with any character. Hold all three punch buttons to fight as Juggernaut or all three kick buttons to fight as Magneto. Note: You cannot switch back to the original character.