After finally getting the chance to experiment with everyone on the roster, and after changing my favorites A LOT, I think I have the characters that I'm gonna primarily use.
Mains:
Zero Suit Samus
Sheik
Greninja
Secondaries:
Dr. Mario
Dark Pit
Charizard
Ness
Lucario
These are the characters that I took the most liking to, and they're gonna be the characters I'm gonna be concentrating on the most, especially in For Glory.
Also, I FINALLY beat Master Core at 9.0 difficulty in Classic mode. I used Ness to do it. The Sabres Form is a total bitch, but I kept my percentage low and my stock at 2 when it came up, and the rest was a breeze.