I'll have to agree with @
Pacack here. Focusing your time on one or two characters is better than having several mains at once. More time spent on the characters so they're more refined.
It takes time and skill and near-utter devotion for me to be this fast.
Playing around with more characters
does allow you to experience how other characters play, so you can learn the matchup or even develop new techniques with them that transfer to your main.
However, actually maining many characters can reduce the refinement of each separate character. As in, if one spends as much time on one character as they would otherwise on four, then they'll obviously have a more refined version of that one character.
In the end, though, it's
mainly up to what you find fun. And in my opinion, trying to try-hard too hard isn't fun.
I think Kirby for me managed to come along as a secondary (well, "2.5", due to Mewtwo) main due to him being my favorite "classic" (read: "2D") platforming character. (You'd expect Sonic to be my favorite in this case, since he's my favorite character, right? Well, Sonic's gone mostly 3D these days, so that's the reason for the distinction.)