Instructions
Choose your other characters wisely. You can pick two other players to fight alongside Iron Man. His Shoulder Cannon hyper attack can inflict 60 hits at close range. You can pair him with projectile players such as Cable. This allows you to still punish your opponent if you use your hyper attack combo from across the screen. Juggernaut's dash form also works well to guarantee that you will knock down your enemy.
Control the tempo of the match. The cheapest method is to constantly fire Iron Man's shoulder missile by hitting down and punch. Your opponent will get frustrated and start jumping toward you. You can use the repulsor blast by rotating a half circle backward and hitting punch.
Bring in your assist characters to prevent your opponent from moving forward. Alter the assists between shoulder missiles. This fills your hyper combo quickly so you can unleash super attacks with all three characters.
Defeat Abyss. Your support characters matter greatly against Abyss. Iron Man defeats regular players much easier than this final boss and his special moves are his greatest advantage against Abyss. The safest method is to use your large character to defeat the first form. Block when Abyss's armor reaches back with his sword. Make sure you do not get stuck in the corner. Unleash your hyper combo as soon as possible.
Use shorter assist characters to your advantage against the second form of Abyss. Get some distance away from Abyss and use a projectile character such as Mega Man. Iron Man's missile works if you are far enough away.
Block until you see the demon's face when trying to beat the third form of Abyss. Use melee combos to build your meter. This third form is susceptible to special attacks. The right combination of players can defeat this form with one three-bar hyper combo as long as you are standing close.