Sonic will probably talk as much as Mario or Link - reduced to grunts, cries, wordless vocalisations. Which should be fine, no?
I don't think they'll have enough time in the approx 80 days left of coverage before Dec 3rd to cover all characters, specials, final smashes, items and stages.
As such, I predict that they won't bother with all of the Pokémon's specials, but they WILL show us the trainer's final smash. I'm thinking it would be the release of a legendary, in the realm of Lugia from SSBM. (Alternatively it could be the elemental hyper beams.)
Anyway, people seem to have a lot of worries about Trainer, but I see it as the greatest and most innovative thing to happen to Brawl so far. It'll be like playing Zelda/Shiek except you have a reason to switch and mix it up a bit, which I always liked to see happen with Z/S.
They said they're changing Bowser, right? That probably means they know he's the worst character in Melee and have made him considerably more useable. I feel that if Charizard really does handle like Bowser, we have nothing to worry about, cause I'm sure they'll know how to make it work. And besides, there's a good chance he'll be able to fly, Kirby-style, which would be extremely redeeming in its own right.