By way of balance,OKW has no medium tanks, no heavy AT guns. It is a long dark wait until KT. Try early medium tank spam while they are going for their KTs instead of waiting for your ISU-152s.
pumas/schrecks and panzerfusiliers AT nade. cheap rakenten, jadgpanzer with 230 frontal armour, all these have no issue dealing with medium tanks.
on the issue with okw lacking medium tank counters, its a myth. pumas are a very powerful counter, too powerful for cost in my opinion. they have
- 50range
- mobility
- escape mechanisms
- good penetration
- fires considerably faster than a medium tank which offsets the 120dmg.
- small target size
the best part, sight range of 50 and able to spot for itself and has a coaxial mg that does more damage than a scout car to infantry.
its cons are that it only has 400hp and without enough pressure or support, can be bum rushed by mediums.
not to mention, it is cheaper than mediums and comes on a very powerful tier with stukas.