I would say Tyranitar but he is based from the first Ultraman monster Bemular, so he's cool looking and not quite so ugly, for simply (as someone said Nidoking and also makes my point) Tyranitar, his function is to dominate, not sit there and look pretty (Milotic comes to mind).
I'd say Ursaring, a savage bear that would tear you to pieces than look at you? Won't be winning any beauty contests, plus it's also looking so angry.
High blood pressure Pokemon anyone?