A total of 4 new characters were explained at Quakecon:https://youtu.be/gL1DLw46W30
Anarki has higher base movement speed at the cost of health and armor.
Sorlag spits acid for area denial (sounds like UT's biorifle).
Galena drops "totems" that heal herself and teammates.
Clutch is a big slow tank robot with some kind of shield.
So much of the negative reaction from fans seems SO short-sighted and premature. So much parroting of "classes are the opposite of Quake" is going on, yet arguably Generations Arena is the most authentic iteration of an id shooter there is, and is distinctly class-based.
In fact, if Champions had started out by introducing Wrack, Grunt, and Visor as based entirely around QW, Q2, and Q3 movement physics in the way Generations does, I feel it would have been much better received by fans, as the first impression would be "classes are making Quake more authentic" as opposed to "classes are making Quake more like Overwatch". I'm not going to hold my breath for QC to be too much like Generations, but I do feel it would have gone over better with the community to at least start out that way.
Speaking of Doom 2016 multiplayer, I wonder if Champions will include Doomslayer with double jump as his main ability. He would still have to run faster than in Doom 4, or he'd get slaughtered.
P.S. there is some leaked gameplay footage on youtube if you search. The allegations that Champsions would not have strafejumping were definitely flat-out wrong.