Co-sign the bolded. We all have those one or two characters we wish could have been in, but the entitlement is really real with this fanbase. Cats want everybody and their mama to be in Smash Bros. We got Ridley, K. Rool, and every character ever from all of the previous games and I still see cats online having legit arguments over Toad, Waluigi, and Waddle Dee
EDIT: I grew up with Mario RPG, and even I don't think that Geno really NEEDS to be playable. If he gets in, cool, but I don't think he's a must-have character by any means. If him and Mallow had been in a few more games then I think I'd be more interested in seeing them, but as it stands now, Geno's a one and done character.