Nothing wrong with pocketing the entire cast, I like doing it myself and I feel I'm at a point where I can use about half of them in a competitive setting and do well enough to hold my ground. I find sticking to one or maybe two characters for too long very boring, so I'm always switching around every other match or so. Being good with most, if not, all characters, understanding their styles and what they do best is also really great MU knowledge to have.
I main Samus, second Link and Snake, and pretty much everyone else I enjoy using and understand fairly well, except Diddy, Pit, Peach, Pikachu, IC's, Yoshi, and Olimar. Gotta invest some more time with those seven.