I wanted to throw this down in here, as I've been making these points to sceptics in the Geno Discord so I thought it'd be time to put them here.
A lot of people are thinking that Square wouldn't have said yes to Sakurai WHEN (not if) he asked if they could have Geno playable. Square has been on a bit of a downward spiral in the eyes of us the consumers in recent history. We want Geno, and Square is doing effectively nothing with him. Consumers hate anti-consumer practices. I think that if Square wants/wanted to turn their reputation around (and they're a business, so they do), they'd want to give the consumers one of the highest requested characters in Smash history. This is merely speculation, but I think that during Smash 4 DLC days, Square said "Okay, we'll let you have Geno but you gotta put a Final Fantasy character in there too" which is how we got Cloud, and then since a lot of resources were spent on Cloud, Corrin, and Bayo, Geno was pushed off to the next game. In the meantime, Sakurai gives us a Mii Costume with a splash screen just to show that he knows what we want. I am a firm believer that the Mii Costumes we got late into Smash 4 are going to be indicative of the characters we get.
The only problem here is that while it's guaranteed that Square and Sakurai shook hands on Geno, it could've been Nintendo executives that initially said no because "who remembers a blue doll from a single spinoff game late into the SNES's life" until the ballot results came in. Of course, we got King K. Rool almost solely off the ballot, as not even the higher-ups at Nintendo were aware of the sheer magnitude of his popularity. I wouldn't say that Geno and King K. Rool got similar representation in the ballot, as it's fairly obvious King K. Rool was one of if not the highest placer on the ballot, but if we're saying K. Rool is a Tier 1, then Geno is among the likes of Isaac and Shantae in the lower part of Tier 1/upper part of Tier 2.
The stars seem to be aligning too much for Geno. Nintendo acknowledging Mario RPG on Twitter with the little Team Geno / Team Mallow thing seems to be the tipping point. Common sense confirms Geno in Ultimate.