I'm personally counting on this since Brawl was pretty much popular-character overkill. I want to see more retro/unrepresented stars rather than more popular side-characters. ñ_ñ
Maybe SSB4 might be the opposite from Brawl...
1-Up Studio (1st party)
Student - Magical Vacation / Magical Starsign (it is gender neutral than Hero or Heroine)
Intelligent System (1st party)
Commanding Officer - Wars series (they don't fight directly, they just command infantry units to do the fighting for them like Pokemon Trainer)
Lip - Puzzle League series
Mallo - Pushmo / Crashmo
Sable - For the Frog the Bell Tolls
Monolith Soft (1st party)
Shulk - Xenoblade Chronicles
Nintendo Entertainment Analysis & Development (1st party)
Mii - Wii Sports series
Muddy Mole - Mole Mania
Nintendog - Nintendogs series
Takamaru - The Mysterious Murasame Castle
Villager - Animal Crossing series
Wii Fit Trainer - Wii Fit series
Nintendo Integrated Research & Development (1st party)
Little Mac - Punch-Out!! series
Mike Jones - StarTropics series
Nintendo Research & Development 1 (1st party)
Duck Hunt Dog - Duck Hunt
Sukapon - Joy Mech Fight
Nintendo Software Planning & Development (1st party)
Karate Joe - Rhythm Heaven series
Maybe there is a little too many obscure characters...