I wouldn't be opposed to a one-franchise specific Smash spin-off - in fact "Super Smash Mario" or "Super Poké Bros." may be the best possible future for the series if Everyone is Here can't be replicated.
I would however be opposed to a specifically themed Smash spin off (Smash Sisters, Smash Villains, e.t.c.)
I would however be opposed to a specifically themed Smash spin off (Smash Sisters, Smash Villains, e.t.c.)
1. The potential fallout
2. How Waluigi acts when not being constricted by an E rating