If you look at the actual power levels, everything is kind of odd, but flavor wise it makes a lot of sense if Nunnaly is the Black Queen, Kallen is a B Knight, CC is a Bishop, Rollo is a B Knight (one that will be traded up sooner or later, for a rook maybe?). I don't think his other Bishop or Rook position is known yet, but I'd bet Ougi is one of his rooks. Maybe Todo though, he might be a rook instead of Ougi.
What about the people in the school? They're not directly involved in the war, but they're clearly really important; I'd bet anything that throughout the show they'll be drawn in one by one into the conflict.