I think using Banjo as a "therefore, Geno" argument is a bit misguided.
MS has only one franchise with any shared legacy with Nintendo, and that's B&K. Fan demand most likely helped, but I can't imagine they would get in if that was all it was. If this was just any other third party, I might agree with that line of reasoning, but we're talking about a platform-holder and direct competitor. Legacy is more important than relevancy in this case because we're literally talking about what was at one point a pseudo-first party franchise.
Geno is also in that weird place of pseduo-first party-ness, but if shared legacy with Nintendo is actually relevant here, then he's far from alone on the Square side. Several Final Fantasy games, TWEWY, more recent stuff like Bravely and Octopath, and that's all just off the top of my head.
Once again, this doesn't mean Geno CAN'T get in, but they're completely different situations, and I already explained my reasoning on the three big rules that Geno would have to break which no other character has including all the fan requests that have gotten in.
Since we are still talking Geno, I have made a list of things in his favor, why he is not in, and what go against him being included. Here they are.
Reasons why he may get in.
-High fan demand
-Sakurai likes him and wants him in
-Good gameplay potential
-Square no longer being stingy with their characters.
-Spirits do not deconfirm
Reasons why he as not in yet.
-Cloud was the last veteran to get into Ultimate
-Hero was decided to be DLC first
Reasons against him getting in.
-Irrelavancy, has not appeared in a game for along time, not counting the cameo in the original Mario and Luigi: Superstar Saga
-Was a supporting character, compared to Banjo-Kazooie and K. Rool, who were main characters and had a bigger legacy.
-Was in one game,
-While the one game he was in was fondly remembered, he was just one part that made it good.
-Not many people outside his fanbase may know who Geno is.
-Accessibility to his games is limited as the rereleases are few in number
-May not be profitable
-Nintendo is choosing the DLC characters, not Sakurai, and thus they may have little interest in him.
-Came from a spinoff and not one game
-He is owned by a different company
-Nintendo might stilll be stingy about letting him in Smash Bros. Ultimate
-Super Mario RPG: Legend of the Seven Stars is obscure, and Geno, by extension, is probably even more obscure.
-Heihachi was also wanted by Sakurai, but Heihachi was added in as a Mii Costume, which could apply to Geno.
-There are other Square characters, let along characters from other companies that could get in before Geno.
Anything I missed? Let me know. Still, the things that go against Geno seem to outweigh the things in his favor. What do you all think?