In my games, each side seems balanced, but the same tactics are used everytime - Germany goes after Moscow.
Germany always plunks most of their $$$ on armor and zooms them to the front lines towards Moscow with their 2 space move.
When I’ve played as the Allies, I just buy as many Soviet infantry as I can and plunk them in the 3 countries right behind the 4 pink countries (forget what they’re called). And I add a few AA guns as a deterrant in case some aerial units come through, although I’ve yet to see Germany build up lots of fighters and bombers. I just let the Germans take over those pink countries and sacrifice the few $$$ to them so I can concentrate on defending 3 areas instead of 4.
The latest tactic I used was doing the above but also slowing sending some troops from the northern Soviet places (and some produced units from Leningrad) to take over the couple scandinavian countries Germany gets right away. This added some $$$ to the Soviets’ coffers, German lost out a handful of $$$ and the Allies have Norway to lanuch SBRs.
I’m new to this game, but I think what I did was legal - using Norway as a launching pad to SBR the Hell out of Germany. I think I had about 6-7 US bombers, 3-4 UK bombers and about 3 complementing fighters for each. A few times I made German lose all of their cash. The UK and US just kept making flying units when they got shot down from AA and the defending fighters.
While that happended, the Soviets continued to stockpile infantry at the front lines, amassing 15-20+ in each one, getting continuously supplied by their ICs. Germany’s tank production never caught up, since the SBRs made them poor. After combining my infantry stacks, Soviets had a stack of 30+ infantry and I ended up marching to Germany that was depleted of units and won.