Pawns can vary in size, from 0.5-2 meter, they're rather easy to beat, but they have sheer number and incredible agility.
Rook-class? They're puny and a single MBT can easily can beat them, in a subversion, so much that JDSF consider Pawns are more harmful than them (usually due to sheer number though). Rook class are more useful as transport and fire support, they're just as dumb as Pawns though.
Bishop are a better fighter and is about 4 meters tall, and vaguely humanoid.
Knights are completely humanoid except for odd stuff like semi-mechanical wings and stuff. They can go toe to toe with an Armored Stratos, and possess intelligence comparable to that of teenagers (but often lacked emotion).
The problem is the King and Queen-class.... 180 meter behemoths that is a nightmare incarnation that can shrug a combined attack from 20 I.S. unit like nothing, and nuke is the only option
