More small stuff: Dirtbags (hills can also trap units), blastwings(burn everything)
More bombs: Any bomb is fine, but roaches are best. If you have amph fac, lobster can throw bombs (dunno is slow bomb would be cost effective, but they might give your grizzlies an easier time). Roaches dont even need to be cloaked in some circumstances, even if domi's capture them, they still blow everything up
More long range annoying stuff: any arty spam would work really: emissaries, badgers (mines also distract domi's), slings+snipers, lances, racketeers, lucifer, cerberus. This just takes a bit more time than the other strats.
If the ball is really clumped up, an ulti could even make cost.
As others said already, the point is to not attack before you have enough to do substantial damage.