But that also means there's a possibility that Geno's Mii costume not returning is not linked to anything other than Nintendo not wanting it back. That was my main point, as missing spirits were used as arguments as well in the past. Something missing does not equal its coming later.I already acknowledged there were others as well, I was just saying it could help. It's not like he's some Bubsy. Sakurai at least specifically mentioned Geno's demand.
No, it's not obvious. The only example we have is Joker, and they could've just monetized the costumes as soon as possible if that were the case. We don't know if 6 costumes is their standard or if they just go with whatever they think works, and bring whatever back. We have nothing to base this off of except for one single case. People were taken aback by the lack of Geno's costume because of everyone crapping on him by saying he'd just be a costume with some being plain rude about it, and Sakurai's words regarding it last game. A lot of people actually think we won't get another SE character except for people who are healthily hoping for Geno and think he has a shot, and of course whoever else for other characters but most of those who are hoping for someone other than Geno aren't even considering his mii costume as far as I know.
The thing about Spirits is that they could've been worked on before Sakurai knew about DLC (January 2018) which I find most-likely considering the whole new World of Light mode, the amount of spirits, nearly each one having a battle, and of course the other Spirit systems they had to code. It's entirely possible he wanted Geno and Mallow spirits beforehand, and Nintendo let him have them because why not so they asked Square, and then when DLC comes around they let Sakurai choose Geno or they even had him on their mind; they could've just not cared about him being a spirit in the base-game (why would they care if he's both playable and a spirit?) so they just said yes before they finished their DLC plans (which it's clear they wouldn't have until close to when they let Sakurai know, and they wouldn't have started negotiations until after that since it seems Sakurai had some form of control based on his tweet).
Spirits lore is also already messed up. You can have multiple of each spirit, including Geno's. There's really no reason for them to be taken so seriously in that regard or for nobody to think about when they may have been chosen in regards to when DLC stuff started. I highly doubt Sakurai would reject the idea just because "well my team and I already made them a png you can receive endless times through a battle so I'm afraid I can't" when he probably didn't know about DLC when he and his spirits team added them, as I said.
yes, theories may not pan out, and of course the theories tied to backgrounds and reveal trailers definitely won't unless it's pure coincidence anyway.
That also means there's possibly no actual strict mii costume pattern or that Square saved the two costumes for later.