Within the Fighters Pass cycle of speculation, I've always felt more optimistic and certain than not in regards to Geno's inclusion into Super Smash Bros. Ultimate. After following the news of leaks, teases, and speculation discussion on the DLC fighters and Geno, I've always thought that we may have been teased from the very beginning without us even knowing. Such hint has been in the base game in the form of the
Spirits mode. Reason why I've always believe the mode to be a hint to Geno's coming is the very concept that revolves around it, as well as the canon lore of Super Smash Bros. (toys engaging in epic battles in the imaginary world, while hoping, trying to one day come to the real world). In World of Light we can pretty much see a form of "Geno's descent" simulation on each Spirit battle; every Spirit is manifest using the body of one of the fighters in the roster (much like Geno in SMRPG manifests itself by possessing a wooden doll).
Outside of the game, there's also the
tweet Nintendo posted about a year ago (or more), asking fans whether they chose Team Mallow, or Team Geno. That tweet when I saw it at the time came out of the BIG blue. I'm pretty sure I wasn't the only one that went, "what the... is Nintendo really tweeting this? WAIT A MINUTE...
".
And not to let this out of the whole picture; back to the game itself, when Hero released along with some DQ Mii costumes, neither the Chocobo Hat,
NOR Geno's Mii costume were included. Sure; since the character being released in the pack was DQ 11s Hero, it seemed natural that the Mii costumes would be DQ themed. However, how come Joker released not just with some Persona themed Mii costumes, but also some other SEGA costumes (Tails, and Knuckles)? The Mii costume's absence certainly raised the chances all the way to Home imo. Potentially Banjo & Kazooie's associated Mii costume wave could in a way confirm if its absence was meaningful or not (i.e., if aside from Banjo & Kazooie Mii costumes, we get at least one or two Rare costumes).
As I've been saying, and I'll say it again. This is my opinion, my gut feeling, not necessarily anyone else's. Geno's coming to Super Smash Bros. Ultimate. If otherwise, I'm ready for the salt.
Most likely he would be the bonus character right after the Fighters Pass.