Personally, I feel like that having an extreme variety wouldn't necessarily be a bad thing and it could probably make each match more interesting or feel more unique in that sense. One counter point I could make about the legendary pokemon are the Master Balls, which pretty much is mostly legendary pokemon to begin with.
So I don't think that more pokeball pokemon would be a bad thing in that regard because there's already been so much done with them that in smash ultimate they could probably get away with as much as they want so long as they keep it within the system's limitations, which have proven to be far more immense than what people thought as we've seen Sakurai go all out with characters and stages in ways that seem to push the console, hard.
With that being mentioned, I think what would be another interesting twist, far as aesthetics go is if Sakurai decides to throw in shiny pokemon and somehow make that a game achievement. But seeing that would be unlikely.
So I don't think that more pokeball pokemon would be a bad thing in that regard because there's already been so much done with them that in smash ultimate they could probably get away with as much as they want so long as they keep it within the system's limitations, which have proven to be far more immense than what people thought as we've seen Sakurai go all out with characters and stages in ways that seem to push the console, hard.
With that being mentioned, I think what would be another interesting twist, far as aesthetics go is if Sakurai decides to throw in shiny pokemon and somehow make that a game achievement. But seeing that would be unlikely.