This (I'm assuming) is the base character pool, without having anyone unlocked. This means that Wario, Pokemon Trainer, Snake, Lucas, King Dedede, Kirby, Zelda, Peach, and Ice Climbers won't be playable until you unlock them. Oddly, that's 9 hidden characters revealed prior to launch!
The strangest thing about that list is that Kirby, Zelda, Peach, and Ice Climbers are veteran brawlers, so you'd think they'd be selectable from the start. Now, I'm thinking that you unlock who you save in the first level as a playable character. So if you save Princess Peach from Petey Piranha, she becomes a playable character, and you have to wait until your next play through to save Princess Zelda and unlock her. However, it's really weird that Kirby isn't listed, because you can select him in the very first stage of the Subspace Emissary along with Mario.
Maybe this character select screen is still a work in progress and I'm reading too much into it. What do you guys think?