I main Olimar, or at least I'm practicing with him so I can main him : )
After him there's a bunch of character that I use, some more than other, but I use them all. I'll try to list them x3
Peach, Marth, Ike, Lucario, Luigi, Ice Climbers, Pokemon Trainer, Toon Link, Snake, Sonic, Jigglypuff, Samus, Ganon, Zelda, and Yoshi. On top of my head in no particular order.
I play with Pokemon Trainer, Toon Link, Marth, Peach, Luigi, and trying to learn Snake more out of the group.