Interesting thing to keep in mind: The guy that asked Hitagi is a KOS-MOS fan and Hitagi did not say no to KOS-MOS. He said not Agumon or Lloyd.
At least it's not a no right now but this is something new to discuss!
I'm still 50/50 on Hitagi. Vergeben seems to be kinda buddy with him/her, so it's possible that there is a level of truth to their cryptic blogging. That being said, I wouldn't place all my cards on them yet.
Assuming they are legit, we can check off Lloyd and Agumon. Now to list off who else KOS-MOS might have to face off against for the Bamco character spot:
-Heihachi: I think he's still a "threat" so to speak. Sakurai's statement regarding him could very well change. On the
other hand, Heihachi's costume was made publicly known mid-2015, and the project plan for Ultimate happened somewhere around that year. It's possible he couldn't find a way to work him into the DLC plans at the time, both for Smash 4's base roster and Ultimate.
-Klonoa: A long shot, but fairly possible I think. Bamco hasn't forgotten about him, and he's marketable enough in a game like Smash. I feel like Nintendo would probably advertise him to reach out to a
certain audience besides the obvious.
-Yuri: Hitagi said "no Lloyd", but while he's considered the face of the franchise in some circles, there are still protagonists Yuri and Luke, who for all intents and purposes are hella-popular as well. Assuming it's neither Heihachi nor Klonoa,
watch out for these two instead.
-Taizou: An obscure choice, but a choice nonetheless. With Bomberman in AT Hell, it doesn't seem likely that his Bamco counterpart will be inflating characters and- Actually, forget I said anything...
Imma just... grab the brain bleach over there and... h-he might work better in a Darkstalkers crossover
-Nightmare/Siegfried: Unless they're visually and aesthetically compared to the likes of Cloud, Ike, and Black Knight for composite reasoning, I think they have a fair shot at being playable (with both being costume swaps of each other, obviously). Their franchise has the right kind of stages and music, and they'd be the first 3rd-party characters to be a playable villain in some form.
-Ummm, ****, who else... Oh, a Souls character! Not Solaire though. Popular he may be, but that's just delving into Sans Undertale territory. If we got one from the series, it'd likely be the Chosen Undead or the Ashen One (or even Artorias, but the dude's kinda
large and
lanky).
Honorable mentions go to...any other Soul Calibur character they'd like to use, maybe even Jin Kazama from Tekken, and maybe even a different Tales Of character that I didn't speak of. They're kinda low priority atm because they bring in their own slew of problems that you can attribute to them like the above main names. I'm lowering my expectations for now, but the "Didn't say no" response kinda gives me hope.
Though I hope Hitagi's silence toward KOS-MOS doesn't imply something else, like a subtle way of going, "Who?" without asking it.