99 Lives

Pause the game.then press Down + C, Up, Left, Up, Right, Right, C.

Invincibility

Pause the game. Press Up + B, Up, Right, Down, Up, Right, Down, Down, Up, B. If done correctly, you'll hear a crashing sound. Unpause the game, then pause it again and press Up + B to activate the cheat.

Note: This cheat does not last the entire game. If your health begins to deplete, pause the game and press Up + B to reactivate the code.

Level Skip / Character Switch

Pause the game. Press Left + C, Up, Up, Left, Down, Down, Right, C. If done correctly, you will hear a laser blast. Unpause the game, then pause it again. Hold Right + C to skip the level. Hold Left + C to change characters.

Walk Through Walls

When the sega logo appears hold X,Y,Z, and mode. When the title screen appears enter up, up, down, down, left, left, a, b+c. To walk through walls hold mode.

Fight Magneto's Clone

First, you need to be on the very last stage of the game (the one with the big scorpion thingy that keeps on trying to flame-broil you). Make sure on this stage that you are not Magneto, or this code won't work. After the scorpion thing explodes, you have to face the X-Men clones. Here's where you have to be careful. You have to face your own exact clone(s) and you have to make sure you haven't destroyed all the clones. When you destroy your matching clone, go as far downward in the stage as you can to where the scorpion's legs turn into clones. Now go to the wall on the left side and hit it. You should get a smiley-face exploding on the screen. From there, take the right (not left) side of "rooms" and go into the "room" that is up two "floors" from where you were. Now go as far right as you can until you reach a small wall. Hit it! and enjoy seeing the power of Magneto's clone! After that you can beat the game.