I am a fan of buying a lot of offensive units (art and tanks) with Russia to help halt the advance of Germany. I have tried building lots of inf with Russia in the past and it becomes very hard to keep the Germans from taking all of Russia’s economy with that battle plan. Of course Russia will need the help of it’s allies because it can not stand against Germany alone in Alpha 2 forever no matter what it buys.
I do not have experience with Romanian Complex tactic by an Axis player. The oppponent I play the most likes to attack Russia with Infantry and Artillery early and then reinforce with tanks and planes as he pushes deeper in.