When the READY signal appears, type in the 3 first letters of characters name to attack. You can switch between the characters by pressing 1 2 or 3. Different timings result in different attacks, go to the TRAIN section wheren you can learn them. X-mens are stronger or weaker depending on the vilain they are fighting, find precious hints in the bios section. When a character attacks get bonification when you use it rarely, it is really important for you to use all of your characters in attacks.