Shovel Knight should never ever ever be in Smash Bros. But I have no love for that game so disregard me.
I don’t really feel that you need any more representation of the Kirby series than there already is, but if any characterwere to make it, it would likely be Bandana Dee.
I think that a more relevant topic when discussing potential roster picks is what games/series don’t need more representation in Smash, or have no more roster potential. Like, the only two characters I can see from Mario are Captain Toad and Waluigi, but that’s scraping the bottom of the barrel. As much of a Metroid fan as I am, Ridley doesn’t work and there haven’t been any landmark, iconic characters out of that series other than he and Samus. Zelda is mega popular right now but any other additions aside from Tingle would be single entry characters. They could capitalize on Hyrule Warriors giving some more representation and moveset potential (Midna, Ganondorf, [and Ghirahim pleeeease!]), which I think would be a bold move. The boldest of all would be adding that game’s titular character, Lana.
Donkey Kong needs another playable character, whether it’s Dixie or Cranky. These are characters I feel deserve a spot, unlike King K. Rool who doesn’t have one distinct personality. Personal opinion. The return of Wolf would be the only entry Fromm Star Fox I could imagine, unless you’d let me to do something with Slippy and his Star Fox Guard appearance. Kid Icarus certainly doesn’t need any new characters, but since it’s Sakurai’s baby I could see another one. I’d want something more unique fromit, like Hades or Medusa, as Smash lacks villains (and yet, I don’t want King K. Rool...). Kirby is fine. Earthbound could use more variety but it’s still too niche to get anything more than what it has.
Then, there’s the two elephants in the room. Pokemon won’t lose its potential additions until a Smash game with ONLY Pokemon exists, but I really feel they should try to be conservative with this series and reserve spots for truly iconic and popular Pokemon. Everyone who is wrong and stupid seems to want Decidueye but I would prefer other grass-types. And then there’s Fire Emblem, which is such a frustrating series in general. With games that feature such a wide variety of weapon types and fighting styles, it baffles me as to why every Fire Emblem character wields a sword. If they were to add another character, I’d pray for an axe/lance user, although to me, I feel you could give a nod to ATLUS and cover your bases with one of the characters from the criminally underrated and under-exposed Tokyo Mirage Sessions. I mentioned this on Twitter.
Outside of that, there’s lots of one-off characters from Nintendo games that don’t need any more entries. The potential of new series being included is much more appealing to me than anything, but I understand that, at its current size, representing Nintendo series is going to be slim pickings. There are certain games that would work better as stages than fighting characters, like Pushmo and Captain Toad, and new series- with the exception of Splatoon- are extremely niche, like Dillon’s Rolling, ARMS, and Code Name STEAM. I don’t think a universe exists where this next Smash will have more third-party additions than first-party entries, but I do wonder if Nintendo will extend a hand to smaller indie developers who have really made an impact on their consoles. There are some universally popular indie titles like Cave Story, SteamWorld, Shantae, and as much as I hate to admit it, Shovel Knight who have honored some traditions that Nintendo has established, and perhaps deserve a spot among the heavy hitters. I don’t see this happening, but hey, no one believed Cloud would ever be in Smash, either.
Also, please leave Kingdom Hearts out of Smash Bros..