Yeah but most characters are pretty unique and arent based on an entire species, then again thats not entirely true as seen from various pokemon and even yoshi, so really idk.
Baby Mario and Baby Luigi have one appearance in an RPG plus various playable appearances in spinoffs, so they can work fairly well, IMO. That's why the Ice Climbers are such great fits for them, lol
I don't know if they should be Mario or Yoshi candidates, though. The babies have appeared rarely in their diapers when they were playable in the spinoffs, so that makes them more like Mario characters, huh?
As for the stork, I'd like to have another bird playable.
Also I would like werehog sonic to appear. Oh and Sonics wisp powers from Sonic Colors. Eggman as a playable character. Mecha Sonic as and assist or Playable.
Werehog Sonic and Mecha Sonic definitely won't be in there at all, Eggman will probably remain a trophy, and maybe one wisp power as an item, probably Frenzy would be most fitting, but I doubt it.