With other EW contenders, the T-34 would not be unstoppable by any stretch. The HVAP rounds should be removed from it in the EW arena, if that is possible to do by arena, and it's ENY would have to be the lowest of any of the vehicles, but there are worthy opponents for it.
The T-34 was a "late" '41 tank, which puts it right at the end of the early war period. One of the more obvious and probably easiest to model opponents for it would be an earlier version of the PzkwIV, probably a D or E version that had a lower velocity 75mm gun. I think the F with a better 75mm gun was a '42 or later, so I am not sure if that would qualify as a EW or MW tank by current definitions. These guns would be less powerful than our current PzkwIV(H), but would be roughly par with the T-34's 76 (again, sans HVAP).
I think in late '41 there were also a few PzkwIII(E) and (J) versions with 50mm guns, along with the earlier versions with the 37mm guns. Frontal shots with a 50mm would be problematic, but side or rear shots would be dangerous to the T-34.
Then there could also be the more heavily armored Matilda tanks from the Brits. The heavy armor might make them survivable enough to get a few licks on the T-34s.
Even another Russian tank like the BT-7 with a 45mm gun could be dangerous. The BT-7 was a very fast tank, outpacing even the already relatively speedy T-34. What a change of tactics that would cause to T-34 drivers who are used to their tanks being faster than their opponents!
I don't think any of these versions are the "equal" of the T-34, but they would be dangerous enough to it to make the battles interesting.
