Warhawks are weak and nobody will send masterminds alone, that's for sure.
Maybe, an AT drone with low hitpoint but fast speed and small range attack will take care of that.
EA have Charons while PF have good artillery vehicles, but USA only option is the Mercury, but it is nearly useless against vehicles.
Bulldog spam is clearly not an effective option.
Now I kinda miss it, the vanilla robot tank. It's suck against infantry, but can still crush them. Its gun was so good at dealing with masterminds, miners and even ships.
I guess you would have to strike quickly in the match, like you would with China or Pacific Front. I would still use Warhawks for hit and run, simply just to slow them down and gain momentum with resources. Now that it will take longer to reach T3, people will have more time to utilize T2 units, and I think this will be the most effective option against PC if you're the US. The point is, you're not trying to deal with them at T3, you're trying to deal with them as soon as possible, rushing them, which is USA's strategy usually. By the time both players reach T3, they should both be weakened that one or the other will likely not be able to build a large enough force to just steamroll. But then sometimes it's just the map, where you're not able to pull off those tactics properly, then I'm afraid there is pretty much nothing you can do but avoid those maps.
But maybe you're talking about 2v2's or higher, I never play them so people building two large armies and then clashing never occurs for me in 1v1s, which is where the true competitiveness is.
How to beat Mind Control Unit Spam: Mass Basic infantry
That might be effective if the person using mind control didn't have Duneriders, Basilisks or Libra in their arsenal. Not to mention that when they have the Cloning Vats, they will probably vastly outnumber the Soviet Infantry with their own. Pointless to even mention Allied basic Infantry.
Long-range or early harassment is the most effective in my opinion.