[serg3d]

From the realism point of view all Zis-2/Zis-4 gun based units only semi-realistic - the vehicles/guns were available at the 1941, but the manufacture of both vehicles/guns and ammo for them was stopped by the end of 1941 until 1943.
That rule out actual use of Zis-30, T-34/57 and 57mm ATG until 1943.
Zis-30 - only small amount was manufactured, the vehicle was unsuccessful. It had low reliability and was incapable of long marches.
T-34/57 - small amount was manufactured, production stopped due to problem with AP ammo, high cost of the gun and limited availability of guns due to Leningrad siege. The vehicle itself had shown some success in combat, then used by experienced crew.
Zis-2 57mm ATG - the same reasons as for T-34/57.Also high velocity 57mm shells were inflicting less damage on thin armored german tanks then lower velocity 76mm.

But from game fun point of view - they are fun to play. And you can consider them as alternate history route.

Also I always pick some KV (company or understrength company) as infantry buster and damage soakers.
The good idea is to pick up some off-board 152mm artillery for conterbattery fire, though that wouldn't help vs german 170mm and 180mm.
I always pick up a company of cossaks with molotovs for forest fighting and recon. After first battle I replace cossak scouts with lancers.
I'm playing with +150 AI advantage, and facing a huge hordes of AI armor. To stop them I have to have infantry with good AT capabilities. I'm using para or marines, or guard later.
My current campaign (unrealistic):

staring with
1 company of T-34/57 (unrealistic)
1 company of KV-1e (heaviest KV around)
1 battery of 57mm ATG (unrealistic)
2 companies of paratroopers
1 company of cossak
1 battery of 120mm mortars
AO BA-20
reserve AO
4 SPAA
1 battery of 37mm AAA
Later added:
1 battery of 85mm AA/AT
1 btn 152mm off-board artillery
M-5 halftracks for infantry (unrealistic)
a lot of komsomolets ammo carriers


By the end of 1942 you face Tiger I. The only soviet gun that can kill Tiger I at range is 85mm heavy AA/AT gun. But 85mm gun have only 15 AP shells, so I always put ammo carrier behind one.