Baisicaly theres a strat to counter anything, I mean carriers? you can kick the shit out of them with BC/GOliaths, Lisks? A few well placed nukes can take anything out. Aim for their gatherers, Thats one of my favorite strats. If you can catch someone without detectors, bam they are fucked. I mean its harder with zerg, but I can get around the overlords

Kill off all their drones/hives and what can they do but slowly die?