I'm not trying to pretend that Graalians will be able to practically pull such a project off, I'm saying it's still technically feasible. It would never be as thorough and polished as a professional game, but it still very possible to create such a server and have it be somewhat successful (on Graal standards I'd say a steady playerbase of around 40 would be somewhat successful). I suppose it's something that's best left as a theory, but with the right team and masterminds behind it, it could very well be pulled off.
Characters aren't really an issue. The original SSB had 8 characters plus 4 unlockables. Jigglypuff was useless and Luigi was almost Mario's clone save a few powerhits and slight differences. I'm sure we could come up with atleast 5 characters.
I mean you have:
The mighty all show no go warrior from GK.
The possibly metro Zone posterboy.
The rough I GREW UP IN THE HOOD yet whiter than a ghost gangster from Era.
This is actually a real screenshot from the screenshot gallery, LOL
Fung Si Yan hailing from the lands of Classic.
The all text magician from Valikorlia.
Secret characters could be...
Pluffy
A monkey character from Delteria
A human character from Bomy Island
A bomy from Bomy Island