5. The movement of energy through substances in longitudinal waves is energy
6. The energy of position—such as a rock on a hill—is
energy.

fumikage isn't really a bird, and tsuyu does have teeth. tsuyu has a transformation quirk which still allows her to be partially human. otherwise we'd have a large frog running around. fumikage has teeth because again, he isn't a bird. his head was a quirk mixture if i'm correct.