Okay, so here is an aggregate list of the top 20 video game publishers from the last decade. Based it off Metacritic's publisher scorecard so some of it is a bit fuzzy, like Aksys can sort of double for ArcSystemWorks despite the companies not being related at all:
Who would people like to see from these companies?
In Smash (Playable)
Bandai Namco - Heihachi, Yoshimitsu, Ms. Pacman.
Capcom - Strider Hiryu, Chun-Li, Jill Valentine, Amaterasu.
Konami - Raiden, Alucard.
Microsoft - Master Chief, Steve, Rash.
Nintendo - Style Savvy, ARMS, Krystal, Jody Summers or Black Shadow mainly.
Sega - Ulala, Tails, Kiryu.
Square Enix - Lara Croft, 2B, Jecht mainly.
EDIT: SNK - Nakoruru, Geese.
In Smash (Non-Playable)
Koei Tecmo - Ryu Hayabusa.
Ubisoft - Ezio mainly.
Not In Smash
Activision Blizzard - Hoo boy. Kerrigan, Crash, Thrall, Raynor, Spyro in that order. All whom I like by the way. (Edit: Oh, forgot Diablo and Zeratul. Add them in too.)
Aksys Games - Not familiar with their games. Leaning maybe towards Guilty Gear.
Bethesda - Doom Slayer, Dragonborn.
EA - If only Mass Effect didn't fall down the drain. Thanks classic EA greed!
NIS America - Honestly, Dunno.
Paradox - They don't have many - if any - good choices for Smash due to the games they develop.
Sony - Kat, Sly, Sweet Tooth
Take Two - Not sure, honestly. Their biggest IP (GTA) would be really wonky to fit in at best.
THQ Nordic - Dunno.
Warner Bros - Scorpion. 10 / 10 addition if he somehow got in.
XSEED Games/Marvelous USA - Dunno.