See, this is why the villain plots for Dragon Ball are not as bad as people make it out to be. Frieza actually never trained at first, so he got owned, Cell was literally a science project who never trained, so he got owned, and Majin Buu was a magically-created abomination who never trained, so he got owned. Only actual gods got away with being broken and unstoppable: the rest were defeated by someone who clearly worked more to get their power than they did, even if said work was glorified gym training, so it makes more sense than the average shonen anime.

Eh, villains typically don't get a master/teacher as great as protags do.