actually, no. mewtwo has a hover. it's called a hover by the devs. that's the precedent that's been set, officially. peach has a float, she's floated since melee, that's the precedent set by the scene.
ganon's nb acts more like peach's float than mewtwo's hover (you don't have omnidirectional control, just slight horizontal drift while slowly descending, hence "Dark Descent"). that's why it's mostly referred to as a float. hover, though, sounds cooler, because "hoverdorf" just flows better than "floatdorf", imo.
but, it can be called just about whatever, and as long as it makes sense, it doesn't matter and people will know what you're talking about (i know i've switched between hover and float midsentence before. sometimes back and forth a few times, in fact >.>)...