If we're discussing just the characters from the trailer...
SSJ Goku
All-rounder. He's the face of the franchise, so there's no way they're not going to have him be the easiest to pick up and play.
SSJ Vegeta
MvC Iron Man. Mid-far range character, good zoning, movement allows him some easy rushdowns, but he's susceptible to rushdowns and has no way to open up his opponent's defense outside of zoning.
SSJ2 Gohan
Pressure character. Fast, high damage close range combos.
Freeza
Mix-Up character. Hard to predict beam attacks and high low combos.
Cell
Dominating, high power with exploitable weaknesses.
Buu
A mix of trapping/Keep away.