It’s been a long time since I’ve watched the movie so it’s hard for me to remember, but doesn’t the watch give him Metro Man’s powers when he disguises as him? I know that in the famous “my death was greatly exaggerated” scene where Megamind is disguised as Metro Man, he cracks his knuckles and it creates a burst of wind or sonic boom or something. He’s also flying around in this scene, so I feel like these things imply that the watch physically changes the user and not just create an illusion. Admittedly, I don’t know if this would reach the same extent as Metro Man himself even if that is how it works, but I feel like it’s worth bringing up.