Russian T-34 tank is not the most powerful tank in the war, since it doesnt have radio, and its cannon is not as powerful as the german most powerful tank (tiger series), the advantage this tank can enjoy over the german tank is the number of tank, in every 1 tank germany can produce, russia produce 5, plus germany has build tanks using materials that is rare in Germany. Moreover, Russia T-34 is build for extremely cold weather, thats why their engine is using disel fuel.
i dont know much about Joseph Stalin tank, but is that possible those tanks are use in the korean war, perhaps the T-34/85 too?
thanks for answering
(more info about T-34/85 and JS tank are welcome)