Jump punches and flying punches are illegal because both feet are off the ground. Yes, if you're talking about practical boxing (not in a ring). The core power factors in boxing punches are three: ground power, inertial power, and rotation around the spinal column. read more
Therefore a punch that uses any two factors can be a hard one. In a jump punch, ground power (the leverage off the ground during the punch and at impact) can’t be used of course, but even so a punch can be effective, and can certainly have knockdown power if the technique is well-trained. read more
If you are refering to the way Superman throws punches, I would not advise trying that in a boxing ring. See, one HUGE problem with that is that the winner is already determined in a comic or cartoon. read more
The superman punch works in MMA because you basically fake a kick and instead go over the top. Plus if you miss-time you can always initiate a clinch while going down. In boxing none of these would fly under any circumstance. read more