Gungans?

You just don't understand the gungan kits and what a debuff is. BB2 marks are dispellable, they're not like Revan's. Somewhere in the gungan kits there's also a clause that makes Phalanx Taunt after the generator loses a certain number of stacks in a row or something like that. And Gungans have a ton of mechanics, debuffing the enemy and cleansing their own team. Boss Nass can mass cleanse his team of all debuffs (except the undispellable ones). 

The challenge with fighting Gungans is getting around the Taunt to get rid of the shield generator so you can start killing them. BKM is one team that can do it in GAC (BKM has an omicron that allows her to ignore taunt and she can call a mass assist). Great Mothers also deal with Gungans well because with Doom, you don't even have to kill the generator, you just delete the Gungan's protection and brute force the kills one by one.