X-Men: Children of the Atom

To activate 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.

To fight among the rocket-filled scaffolding of Juggernaut's stage, start a 2P game with Juggernaut being one of the characters. Allow Juggernaut to defeat his rival. The losing player should then press Start, once on Juggernaut's face and again on the Space Port as they appear.