I guess I'll tag
Franco Geno
here since I'm technically responding to him, but it's less about new information and more that all the old information we have is just flat out too damning to be beaten by what is essentially repackaging old assets. However, I don't really have the luxury to cover every single bit of evidence Geno has all in one post at the moment, and I would also have to sort out things and people that can and can't be spoken about, so I'm really not up for it at this moment.
However, I will address one topic in particular, and that is of this likely bonus fighter that was skipped over for whatever reason that may be. I know it's gaining a lot of traffic and at this point everyone has come to their own conclusions, but there is something I think people really aren't addressing when they talk about a bonus fighter, which is the fact that if we do get a bonus fighter they HAVE to be first party. Thus, Geno isn't a bonus character.
Now of course only Siths deal in absolutes, but please hear me out on this, as all previous instances of DLC support this.
Going back to Smash 4, remember that originally Mewtwo was going to be the only DLC until that was changed in development. Thus, Mewtwo would have technically been a bonus character similar in status to Plant, and still fits the bill as he was free to those who bought both games much like Plant was free to those who pre-ordered Ultimate. Mewtwo is a returning veteran from a franchise well-represented with characters, stages and other content, thus he came alone.
After that were Lucas and Roy, both again veterans who's franchises had representation without them. Another way to look at this is that they already came with their own content back in Melee/Brawl in terms of stages and whatnot, so they are just returning without anything new. It's not until Ryu that we see a character come with a stage and music, and wouldn't you know it, Ryu is third party.
After that comes Cloud, and while his lack of music was a meme made up by very disappointed fans, he too came with a stage and music. So did Bayonetta, but as you notice, Corrin/Kamui did not get a stage, only some songs. Now you could argue many things about why that was the case: it could be the lack of time Sakurai had to study the game to pick a proper stage, or the fact that Fire Emblem already had enough representation, or maybe it had something to do with how Sakurai's team convinced him to choose Corrin and Sakurai wasn't as invested (which I highly doubt), or the fact that he was already moving on to Smash Ultimate development could have had an effect. Regardless, duly note that Corrin both did not get a stage AND are first party.
Now on to Ultimate, starting with Plant, you see that Plant didn't get it's own stage. Once again, arguments can be made that a lack of time can be attributed, or that Mario had enough representation, but I would argue for both Plant and Corrin that if their respective franchises had enough representation then they themselves wouldn't exist, but one can have an entire debate about that. Just keep in mind that Plant is also first party.
To try and keep things brief and not be unnecessarily wordy, if you look at all the rest of the DLC for Ultimate thus far, the only first party we have are Byleth, Min Min and Pyra/Mythra. Now Min Min and Pyra/Mythra are both first party, but they are also first party who's franchises are new to Smash, and them coming with stages and music when brand new to Smash is nothing new. The real outlier here is Byleth: first party, but gets a stage and plenty of other content, despite being from a franchise already represented. This goes against what we have already seen, and you might think this blows a hole into my conclusion, but I personally believe this bolsters the claim that Corrin would have gotten a stage to represent Fates if Sakurai hadn't already been moving to Ultimate. In other words, I would compare Byleth with Rosalina & Luma, every Pokemon since Melee other than Incineroar, or literally any other Fire Emblem character other than Chrom or Corrin since Brawl.
See, I think whenever possible, Fire Emblem will be treated just like any other major series Nintendo has, much in the same vein as Mario: whenever they get a big new game, they will add big new content to Smash when possible. In fact, I think Incineroar suffers from the same situation as Corrin and perhaps Plant: we didn't get a new Pokemon stage because of a lack of development time combined with lots of representation already packed into the game, so they chose to just add a new character. However, there was enough time and Three Houses was such a big success that it got it was warranted to get more than what Fates got.
What this boils down to is that, out of all the DLC, the only times we ever got a character with next to nothing else was when it was first party. This is why Waluigi is the first thing to come to people's minds when it comes to a bonus character more often than not: consciously or not, they realize that he is first party and really has nothing to bring to the table that isn't already in Ultimate other than himself as playable. However, Bandanna Waddle Dee, Dixie Kong and the silly talk about characters like King Boo would all fit under this banner as well, and I'm sure you could think of more given enough time. What doesn't fall under this, though, is third party.
No single third-party character, base game nor DLC, has been a bonus character with no other content, going all the way back to the first third party inclusion of Solid Snake. Sakurai has stated himself this, but we all know that Smash has turned into a game that meshes worlds from games all over, and Ultimate is basically Video Game Hall Of Fame. So, knowing Sakurai's love of gaming and dedication to accurate portrayal and how big of a deal getting third party characters is, what in your right mind would make you believe that a third party character would get negotiated for without the bombastic fanfare of a badass stage, as much music as you could get, and a handful of spirits? At this point, if Sakurai came to you and said that he wanted your character but had no plans for any of that other content, as the owner of that IP wouldn't you feel a bit slighted?
So if you want to skip to the end, as I'm basically done here, here's your TL;DR:
Both common sense and logic team up with past precedence to state that a third party character will never come without tons of content alongside them, and Geno is a third party character, so he's either one of the last two here or he's in the next batch of DLC.