We know there are 20 "playable" characters. With the 4 teams we know about, if by playable they mean "can be used on the track" (rather than being the head character you're using), that's 12 characters there. There are 8 friendship orbs in another trophy image which brings that to 20. Due to this I don't think Kairi will be playable in the rhythm section, which is frustrating as hell. It'd be a nice surprise if she was a secret bonus character but I'm no longer holding my breath.
But I'm not convinced that you can't use the different teams in story levels just yet. The image below shows there's a little diamond underneath the Sora, Donald, and Goofy team with arrows next to them.
Timeline is a bit muddled due to BbS, but at this point in the series Days has happened so I do wonder if you have to unlock the teams first and once unlocked you can use them at will, a.k.a you can use Sora, Donald, and Goofy at this point or you can use Roxas, Xion, and Axel. BbS's timeline throws a wrench in this because if they were going by in-game timeline then BbS would have been first, but by going by the release timeline of the games, Days would be after KH2.
But that trailer was whack anyways so idk what to believe in it. It says the player has unlocked the all clear reward for Twilight Town but then when it shows the song selection menu it says the song hasn't been played once lol.
Edit: Not true, I'm a dumbass
I stand by thinking a demo would be the best thing for this game, and I hope they announce a world-wide one at this TGS event. Just give three songs (one battle, one field, one movie) with all difficulties and have us choose what team we want to use alongside a message that tells us these choices aren't only available in the demo and we'll be golden.
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