I wanted to chime in on that leak, and also giving my support for it and you Geno fans with something that I've thought in relation to it and why I feel it's not only real, but it's also lining up with Doomslayer being either the last fighter in the pack or a post-pass character.
Now, the Geno costume was more or less the catalyst for an influx of support that Geno's gotten in the last few years. You'll also notice Geno got a splash screen, unique to him and him only.
Now everyone thought Geno was coming back as a costume and then coming as a fighter thanks to the Grinch Leak. And neither happened. And then comes the leak with the Mallow Hat and Cacodemon Hat. Now why those two specifically? Wouldn't it make sense to show Geno's costume? And then I see the cacodemon hat. Why the cacodemon and Mallow together? Either this is an elaborate troll that's trying to play with people in a more detailed manner like the Grinch leak using those hats to sucker people into thinking Geno's coming or this could be a way to commemorate Geno and Doomslayer's inclusion in Smash Bros. Granted, it could be another character from Bethesda, but then, why the cacodemon specifically? Why not show off Doomslayer's costume unless it meant he was coming as a playable character? This isn't like the other companies' situation where you get Goemon and Akira costumes due to having stake in the roster; Bethesda would have to have a character coming if the cacodemon is anything to go by and if it's the cacodemon being presented as a costume, who else would go well with it other than either a Doomslayer costume or the Doomslayer himself?
This also applies for Geno, given Mallow's hat which we could have gotten in Smash Four or it just means we get a Geno costume and a Mallow hat as a bonus. Right?
Well, here's where that boggles me and why I think the leak is real: Other supposed insiders are denying it and modders have dug into Ultimate and tried to replicate it and all the results have been poor if not impossible due to how Mii hats work this time around. If this were a mod for Ultimate, it would mean someone has come to groundbreaking results for Ultimate modding. But then if it was a fake and someone admitted to it, they'd have to show their work. Every attempt to try to debunk it has only gotten far as to get the model in the preview screen, never an in-game match due to the game crashing if the costume's filesize is too high. So with that said, this could mean
-The leak is real and we're getting Geno and Doomslayer soon
-The leak is real, but we're getting Geno and Doomslayer costumes with Mallow and Cacodemon
-The leak is just modded footage of Ultimate and someone knows things others don't and won't share
Any of the above is possible. But then I consider that Super Mario RPG is available on the SNES Mini and Sakurai more or less has the rights to Geno and Mallow already via spirits, so why not go further and add Geno as a fighter now that the base game is out and situated? Square would also get a cut of the sales directly if the rumors are true about Cloud barely making it in due to their stinginess. I repeat, any of the above scenarios are possible but I feel that the first bullet is very likely. Doomslayer fits with Reggie's statement on characters you wouldn't imagine being in Smash and Doomslayer is from an IP more known in the west, said region getting a few bones with Ridley, K. Rool and Banjo.
Plus to me, this would be another vindication to another fan favorite going back over a decade and in this case, damn near two. I played Super Mario RPG and saw my godbrother play it on release and way before Smash was in my mainstream life, I played and loved the game and its visuals mainly and saw it as a unique RPG with a flare still not seen in Mario's world as of 2019. A time capsule showing Mario's ambitious beginnings in branching out of the platforming genre. Geno wasn't on my lists, but I understand and saw his support way back and know that he'd be a prime candidate for the DLC, if only to stand by the Ridley fans and in my case, the K. Rool/Banjo fans as finally putting to rest the argument of relevancy and other asinine arguments for why a character can't get in as a playable, Sakurai himself stating that a character's relevancy means nothing so long as they're fun to play, another possible hint perhaps?
Last thing to consider with that splash screen: It was shown right around the time Sakurai was composing his project plan for Ultimate. Perhaps this was his way of seeing Geno fans some type of way knowing Four was pretty much done and the Switch being around the corner and wanting to wait for another chance to get him in Smash as a playable character. With the base game done, wouldn't it make sense to try to push for Geno as a fighter instead of bringing back the costume if it got its own splash screen? It wouldn't have the same impact twice. If Mallow was shown in that leak as a hat, wouldn't that further prove Geno's chances to be ripe for the next or near-future reveal? Especially if the cacodemon hat was alongside it and not a Doomslayer gunner costume?
Short version: I stand by the leak and feel that he's likely to come alongside Doomslayer. Count me in as one of Geno's supporters.
The stars shine brightly this fine night.