All Working SNK vs. Capcom: SVC Chaos Cheats - Xbox

Mars Alien
Hold [Start] and press [Up], [Down], [Right]x3, [Up], [Down], [Left]x2, [Down], then any button at the title screen.

Goenitz
Hold [Start] and press [Down]x3, [Right], [Down], [Left]x3 at the title screen.

Evil Iori
Hold [Start] and press [Up]x3, [Down], [Left], [Right], [Down], [Left] at the title screen.

Demitri
Hold [Start] and press [Right]x3, [Left], [Up], [Right], [Down], [Up], then any button at the title screen.

Zero
Hold [Start] and press [Up], [Right]x2, [Left]x2, [Down], [Up]x3, then any button at the title screen.

Shin Gouki/Super Akuma
Highlight Balrog at the character selection screen then hold [R].

Shin Mr.Karate
Highlight Kasumi at the character selection screen then hold [R].

Red Demon
Enter survival mode. Defeat the opponents until you face the Red Demon. Defeat him to unlock him as a selectable character in all modes. To choose the Red Demon, highlight Tabasa, then hold [R] and press [X], [Y], [A] or [B]. Note: The Red Demon is one of the best fighters in the game.