SMAASH! Puppy
Smash Legend
I feel like Demise should be Girahim's Final Smash rather than have Demise playable, but this is probably off of unfounded notions of Demise's lack of popularity.Then there’s Demise w Ghirahim, even though demise is currently only in one game he is very important to the entire lore of the franchise because he is the ultimate big bad who started everything, ghirahim is also pretty popular and with a dual moveset that allowed demise to change ghirahim from sword form to human form on command ala stand style would be very unique.
Also, I think Vaati is a recurring villain, but he's only appeared twice or something.