Just the infantry, but Marines don't need special help killing troops. Then the tanks obliterate it.
That's actually how my game with Matt went last games day. Those fancy rocket marines I painted recently killed everything with two legs, while my vehicles did nothing but die to Matt's Russes when I carelessly left them in LoS. Essentially we ended up in a position where I had nothing but infantry and Matt had nothing but tanks, which favoured me greatly in the scoring department even if the fight itself was a mutual mauling.