Units need to be toned down. In groups of 3 they are impossible to kill. The T70 had a lot of difficulty. If you yield a KV8 you are screwed for the up coming Super Tanks of the OKW.
Wow, 1200mp?! what have you been doing the whole game? Nearly everything is hard to kill in groups of three
Seriously, there's a wide array of counters available to deal with Obersoldaten.
Soviets;
-Maxim to suppress+any infantry to deal damage
-Any sort of vehicle
-Snipers
-Indirect fire
-Shocktroops but only if you manage to close the gap (hint, truesight/ smoke nades)
Even Guards can stand their ground when in a favorable position because their PTRS penetrates the Obers Armor and you might land some crits. Just make sure to retreat soon enough.
USA;
-.50 cal to suppress any inf to dish out the damage
-volleyfire (haven't tried post patch so might not work anymore)
-any sort of Vehicle except ambulance

-If you have them around and you should have them around lategame, vet3 rifles with BARs or 1919s
John Moses Browning developed some damn fine pieces, use them.
Ofc the effectiveness of counters varies strongly depending on your opponents skill, but the ones listed above are the ones I had most success with against Obersoldaten.