Honestly I have no expectations for who could be DLC at this point. It could literally be almost any character in the history of Video Games. Although I do have a few dream characters from 3rd Parties that I'd like to have in.
I find it funny how someone wants Sol Badguy in as ASW has a few characters (Sol aside) that would and should probably be in. I'm of course talking about the Hot Blooded Kunio and/or The Double Dragon Twins Billy and Jimmy Lee! I mean think about it, these characters a great brawlers with a variety of different moves, especially Kunio (from the River City games). Although really I'd assume Billy Lee would be playable out of all of them with Jimmy Lee as his alternate costume. Although you could get a Bowser Jr. sort of alternate character costumes regarding variety with Kunio's being different characters from the series. Either way those guys are my first ASW choices.
Speaking of another retro choice, I gotta go with Ryu Hayabusa. Ninja Gaiden was so prominent in the NES Days and while the character has changed over time I'd still say he'd be a great pick. I mean he'd be more noticeable than say someone from Dynasty or Samurai Warriors but that's just me.
This one is a bit of a bias on my part and he has been everywhere in fighting games lately, but Terry Bogard would be great for Ultimate. He's got a good moveset and a great attitude, plus he's an iconic character for any fighter fan out there. Plus you got that Capcom vs. SNK appeal as well. Not to mention his Train stage from Fatal Fury 2 would be perfect for Smash, and you'd have so much great music from SNK to go with it. How could I not hope for an SNK rep?
Other than the usual picks for DLC 3rd Party hopefuls (Crash, Banjo & Kazooie, Lloyd Irving) that's about it for me. I mean of course there are others as almost anyone could make it in, but I do have to wonder what sort of 1st and 2nd Party Characters could make it as DLC. Besides whoever's the main character of Fire Emblem The Three Houses anyway.