Their NEEDS to be an arty/air cap. I'm not talking specific unit cap, but a arty and air limit per team. Even on normal level points the amount of arty and cheap air a team can put out is unbeatable. You cant counter the arty as the 25 ghetto helo's gang rape everything, and you cant counter the helo's without getting shelled by 45 arty pieces that can reach across the map.
To quote SC2, this is a CHEESE tactic.. an extremely effective one. Their will be those that come in here whipping around their epeens saying "OMG just counter you n00b." But having just played against a straight arty and ghetto helo team in a 3v3.. I can attest that their is no counter to that. And it also just ruins the premise of this game imo...
Tunguskas and Gepards resist a ton of arty and destroy air.
Use more armored AA, simple as that. Also, AA choppers are your friend - IMMUNE to arty in flight and destroy choppers. Arty is useless without spotting, chase down those spotters.