Go to Vs. mode. Type lf2.net in the random menu to unlock Fierece, Black Knight, Moon, Davis SX, Julian, Firzen, Davis SX, Tiger, Songoku, Woody SSJ5, and all other army-related characters.
Transform into your enemy
Play as Rudolph in Versus or Stage mode. Take hold of your enemy by punching him continuously, then quickly press [Defense] [Jump] [Attack] to transform into them. Quickly press [Defense] [Jump] [Attack] to turn back into your original form.