Interesting thing to note about Geno: There were 6 DLC Packs for Mii Costumes. Geno was the only character for DLC Pack 5:
https://www.mariowiki.com/List_of_Mii_Outfits
I'm not sure why this was done, but he also was the only Mii costume to get a title card:
So yeah, Geno has a bit of special treatment by Sakurai and the Smash Developers. There is a reason why people think he's likely in this time around (If Square gave them the right to make these costumes, what's the problem for letting them work on an original character?)
Additionally, if the inclusion of these Mii costumes and their potential sales point to anything (so far, Chrom, K. Rool, and Inkling are in, while Ashley, Knuckles, and Zero are Assist trophies), then the following Characters could still be considered as potentials for Smash Ultimate:
Isabelle
Heihachi (Bamco)
Akira/Jacky (Sega)
Black Knight
Lloyd (Bamco)
Viridi
Monster Hunter (Capcom)
Geno (Square)
Gil (Bamco)
Majora's Mask
With the rest of costumed characters being deconfirmed (either being Assist Trophies, part of a Final Smash or move (Toad), etc).
So going over each:
Isabelle: If Vergeben is correct, she is in
Heihachi and Lloyd: Being Bamco characters and Smash now being a Bamco created game, these costumes may have been added because of this reason (to see if there is any interest in a Bamco character for the game). Either could happen, just don't know IF they'll happen. Could be either AT's or Characters.
Akira/Jacky: Sega reps. To me, Virtua Fighter just seems like a lesser Tekken/Street Fighter in terms of competition so I'm not sure if they'd ever be considered. At most maybe an AT.
Black Knight: As per the screenshots posted before, his absence in the background (if its him) may hint at his inclusion if Sakurai wanted to eliminate redundancy. Echo fighter for Ike is possible.
Viridi: I
could see her happening, but I'm not sure how much priority Sakurai would put for her over Medusa, who'd fit better as an Echo fighter (but perhaps he makes her one with different proportions?). However I can see both happening over someone like Hades. She could be a very cool AT however, while Medusa takes the role of Echo fighter.
Monster Hunter: It being conspicuously absent from Rathalos's trailer and likely the difficuly in making a balanced moveset (You'd have 14 different weapon types to choose from) possibly means its not in the
base roster at least. I don't see him/her being an AT, since Rathalos is in, but perhaps a DLC character in the future since Monster Hunter is more popular than ever before.
Geno: Explained earlier. I have reasons to believe he is in the game.
Gil: I actually see this being the surprise/wtf/retro character. It, however, is yet another 3rd party character owned by Bamco. Like Lloyd and Heihachi, I'm just not sure what their reasoning was for including this Mii costume, only that its possible Bamco wanted the Smash 4 team to gauge who fans might have liked out of the 3 while they worked on Ultimate post-2015.
Majora's Mask: This is a tricky one. The mask is not a character, but primarily owned by Skull Kid. However, due to Skull Kid's "hints" (possible removal as an AT/Replaced with the Moon, item that performs his exact same function as an AT, Young Link's final smash being hidden, remixed MM music in Ultimate, Termina returning, etc) and common acceptance as a possible character for Ultimate, I'll say that its possible he is a character.
So out of all of this, if I had to guess, based solely on Mii Costumes:
Unique Newcomers:
Geno
Skull Kid
Heihachi/Lloyd/Gil
Echo Fighters:
Medusa
Isabelle
Black Knight
AT's:
Viridi
Akira/Jacky
Heihachi/Lloyd/Gil (Whomever does not get a newcomer promotion, perhaps none receive one)
I want to make it clear that aside from these characters,
everyone else from the Mii costume list is represented so far in Smash Ultimate in some way, new or old! Be it an assist trophy (Ashley, Zero, etc), actual newcomers (K. Rool, Inkling, Chrom, etc), final smash assets (Proto-man, Mega Man .exe,
And just to make clear: This has nothing to do with characters not on this list. Ridley was not a mii costume. Dark Samus was not a Mii costume, Daisy was not a Mii costume. Isaac, a pokemon, Banjo, Bandana Dee, Albert Einstein, and George Washington all still have the ability to get into Smash.
In all seriousness though, this just may point at who we could expect outside of other obvious characters.
Any thoughts?