GungHo: I'm counting NMH and Grasshopper Manufacture under this umbrella since Suda's still (at least technically) under them, although Suda operates rather independent of GungHo. Travis does have the favor if needed, so that's a major boon. GungHo's other IPs (Puzzle and Dragons chief amongst them) are more in background. Pretty high up.
Konami: Yea as said previously, I don't see them having a good chance. They have quite a few classic characters on the table still, but nothing clear-cut. Lower half.
Ubisoft: Has a couple characters still on the table, the most notable being the Prince of Persia. However, the negotiations surrounding Rayman have not yielded a playable character (so far at least) and Altair's Mii costume was introduced to the tune of Ezio's theme. By the looks of it, things have stalled. Lower half.
Nippon Ichi: The Disgaea guys? Could kinda see that, although (I was so tempted to make a F1 joke based on their logo and name) N1 only have them really. Would need Sakurai's favor IMHO. Middle-lower half.
Marvelous: Story of Seasons is a major boon to them. Rune Factory 5 and Daemon X Machina helps them quite a lot too. Still, they're in some stiff competition, and would appriciate Sakurai's favor. Decently high.
Cygames: Maaaaaybe? They have Granblue, the Nintendo connection in Dragalia and idolmaster, so they have some stuff. However, Cygames weren't exactly happy with Nintendo's involvement re: Dragalia, so any FP2 appearance would have to be counter-balanced by a more positive factor. Lower half.
From Software: Eeeh? Could see them, but it's mostly Dark Souls' protagonist. Still though, that's a major character by itself, so one shouldn't count FromSoft out. TIL that From Software and Spike Chunsoft are cousin companies under the Kadokawa conglomerate, so one could theoretically put both in the same box. Middle of the list.
EA: Doesn't stand much of a chance. EA has a surprisingly strong list of characters... but the company's history and how they got / handled said characters leave a sour taste in many mouths. OK, Konami's also handled their characters badly, but EA's been associated with it for much longer. Near the bottom of my list.
Sony: Nope. Nintendo and Sony are still rather cold towards each other, and IMO it'll take at least some more time until Nintendo's behind-the-back move towards Phillips / betrayal heals. Bottom of the list.
SNK: Nope. They went all out with Terry. Bottom of the list.
Not India, Indies!: A vast collection here, although indies do not have precendence with them. However, there's still enough to make up a sizeable shot - Reimu and Quote in particular. Highly up, contending for Top 5 IMHO.
Considered Taito, but they're under Square-Enix. If counted as their own company, would be "Nope" because the Space Invaders and Bubble Bobble have to compete with S-E's roster and neither of those strike me as primary DLC candidates.