Even though two out of three of the first few that I mention aren't villains, id have to say that it would be pretty cool if Pitt, Dark Pitt, and Palutena were in Zelda. That would be a really awesome crossover! I'd have to disagree on the point of Dark Mario, however as an alternative I suggest Chaos or whatever his name is from Sonic the Hedgehog. I really want to see like kick his a$$. Also, this may sound stupid, but like, Saron from Lord of the Rings would be very interesting as a Zelda villain. Also kind of funny.