The best one is Hades or Medusa. Ill take Medusa as she is the only main villain who is female. Also i thinl Hades would make for a Masterhand/tabuu boss character in the single player mode
True, we don't have any playable female villains, and Medusa is a great choice. :)
Shadow or Akuma could both be in. Wildcard pick, Tom Nook!
Shadow's less of a villain and more of a rival. Metal Sonic would be the better echo fighter of Sonic because he's actually evil, even serving as the villain in Sonic Heroes.
Tom Nook's just a sheister. XD
Eggman, Team Rocket pokemon trio, Skull Kid.
I like Skull Kid as a playable character, but someone even better would be Ghiranim from Skyward Sword. There is just something so wrong with him!
Eggman would be a lot of fun building a moveset for, because he'd use weapons and gadgets from his various vehicles and Badniks. :)
I'd love to see Bald Bull or Super Macho Man! That'd be absolutely unexpected
I'd say King Hippo, but his villainy is up for debate, because in Punch-Out on Wii there's a cutscene of him saying he'd like to take Little Mac out to lunch.
Would like a Kirby villain. While most are really tricky due to form and size, maybe base Marx, Magolor or swordmaster Dark Matter.
Dark Matter's the best choice, because unlike Marx and Magolor he STAYED evil.