Yes there was guards.
Sadly I didn't save the replay, so I will describe as best as I can.
It was on Semoisky winter, I picked elite troops. 1 mg 3 gd 1 st 1 mortar opening
Decided to skip tier 2
Then he pulled out a ton of cons + katyusha
Then I started to lose the map
Late game he just spam T-34/85s and ppsh cons, squad wipes everywhere
I built stuGs to counter T-34
But seems doesn't work out as intended
As far as I know there isn't a soviet commander that has Guards, T-34-85s, AND ppsh conscripts. I'm going to assume you mean T-34-76s.
Anyways, first of all veto Winter Semoisky as that map is heavily allied favored if you spawn north as axis while also being quite a poor map.
Moving on from that if a Soviet player is going PPSH Conscripts spam then going 3 grenadiers and 2 HMGs will counter his build if using the HMG correctly. Elite troops is actually a good counter to PPSH cons as you can use the stun grenade with G43s to protect your grenadiers when cons try to rush or use Urah to close the distance. Stun grenades also allow you to counter flanks that otherwise would force you off or to retreat squads as you can stun a flanking squad for those few precious seconds to allow your HMG to either relocate or give Grenadiers time to deal sufficient damage to force the Cons off.
Guards are a bit trickier but mortars are a soft to hard counter and what I mean by that as Guards are required to stay still to fire their weapons so by getting a mortar they have to always be on the move or get bleed by the mortar. However saying that you do require a little bit of RNG in that your shells are hitting pretty consistently to inflict bleed on Guards given how tough they and their DPS is quite high meaning any screening grenadiers will quickly be killed. Why the HMG is so important to have too.
You can supplement one grenadiers with one PGs as they hard counter PPSH conscripts as they deal sufficient damage from range to close range that any conscripts trying to assault them will quickly lose models.
Concerning Grenadier upgrades I wouldn't bother with the MG42 against Conscripts anymore just got full G43s.
I'd also recommend getting PGs with shrecks for AT on that map given how many shot blockers are in the middle. Or the very least having a AT gun AND PG shrecks as they can deal with any flanking armor.
The thing about the Katy is you can move out of the barrage area given it deals it over time compared to say the panzerwerfer. Keep your troops spread out will also reduce the danger the Katy will do to your infantry.