Look I dont dislike Geno but he just feels kinda boring to me in regards to the stuff he brings into Smash, which lets be honest its just pretty much just more Mario.
I have great memories of Super Mario RPG, its the first JRPG I actually finished about 22~23 years ago (and passed from the first screen lol) and I still believe its a great game. My last playthrough just a few months ago, I kinda just remembered that Geno was kinda boring storywise and that Bowser pretty much carried the game.
If I was 20 years younger, maybe I would be totally on board with the Geno train. But after playing a lot of SE RPG titles, including FF, DQ, BD, Mana, Valkyrie Profile, the Ogre series, KH, Nier, the absolute masterpiece that is Chrono Trigger, etc, its a title that I don't really care to see over many other possible choices.
The real thing I just dislike is the overall underplaying of SE franchises in the discussion sometimes as I firmly believe even without another FF rep or DQ rep, you could maybe make another pass of SE characters (a pack consisting of BD, Nier, Tomb Raider, KH, CT, Deus Ex would be a dream for me), 2 or 3 if you allow more FF and DQ.