25 munition GP mines and AT grenades. 40 munition button (doctrinal). ZiS-3 - effective against armor and can barrage against infantry. T-34/76 with ram nullifying ANY Axis armor. T-34/85 (doctrinal) with ram AND a gun that penetrates the front armor of any Axis vehicle. SU-76 with decent penetration but bad damage and low health\armor. The T-70 that rapes any light vehicle and snipes infantry. ISU-152. And IS-2 (Admittedly, a shitty tank because of it's cost/speed/penetration). Let's not forget abilities like bombing runs and the 152mm howitzer.
All of these options are available to the Soviet player, yet the ONLY one you see EVERY game is the SU-85. Not because the other options don't work, but because the other options take a certain amount of skill and carry some amount of risk. Why bother with that when you can spam a relatively cheap, non-doctrinal unit that can frontally engage any other non-doctrinal (and most doctrinal) axis units with impunity and requires minimal support to be effective? A brain-dead hamster can micro an SU-85. Countering one requires skill. Countering more than one requires an Elefant.
AT grenads do nominal damage, please try killing a P4 with just AT nades and see how it works. button does no damage to tanks. ZiS-3 has to be stationary and only works in a difensive manner but it is a viable AT option. Ram also nullifies the the T34 and with only a 20 fuel difrence you will not have more 34s than P4s for more than a min.
The t34 85 is over 200 fuel investment making it a "im already winning" button and is doctrinal, the penertration on the 85 is actually lower than the P4 i bleive which throws your argument out the window, the Su-76 has a really bad gun for taking out armour at medium tank status or higher and it made out of paper.
At means anti TANK so light vehicles do not count and with that the t70, ISU 152 and IS2 are inthe same boat as elephant, bombing runs have a CD and hte howitzer comes too late AND it too inacrutate to be relied upon.
Soviet Anti Tank options are ZIS3 and SU85 everything else are support units for them.