Captain QQ covered most of it, but I will add the things he forgot to add.
As for artillery: Apart from ML-20 and KV2, the game also features ISU-152 when it comes to 152mm artillery guns. The unit is available from about 2 commanders and it is very good at killing soft targets at long range - namely squad wiping. Do not use it in large team games though as it's efficiency is very low if opponents have access to heavy tank destroyers like elefant or jagdtiger.
As for AT: Apart from already mentioned zis guns and su-76 assault guns, soviets also have non doctrinal su-85 which is the best soviets have when it comes to dealing with heavies. Using commanders you can also choose to use T34-85s or IS-2s as your AT. You can also just flank with a horde of T34-76es. Don't forget to tech AT granades for your conscripts, they help a lot by slowing enemy tanks. Some commanders also have IL-2 plane abilites that help with tanks. These are:
1. Mark target - increases damage taken by chosen tank by, I think, 33% and gives sight with a recon plane flying over it. It is available in many commanders, often the meta ones.
2. AT bomb strike is an ability available only in AT commander (the one with conscript PTRS). The bombing strike comes quickly and can deal even with more than one tank if they are close to each other.
3. IL-2 bomb strike - another bomb strike available in multiple commanders. It takes time to arrive so it is good against tanks only if you use lots of slowing abilities or crits. But it can be used that way. It is also good against okw forward bases.
Btw, there is a fun fact about the mentioned propaganda artillery. It can retreat all the infantry squads and weapon teams, even the ones that can't be normally ordered to retreat by their owner like for example AT guns. Vehicles are immune to that ability.
thanks that was a tip i will bare in mind