Russia only has to counter pressure from the east and south with minimal resources. The great prize for Russia is grabbing german territory to the west.
My main strategy for Germany is to make as strong push as possible towards Russia early. I usually wait to DOW until G3 though, since Russia get a strong boost from NO’s. The two turns will be focused on mobilizing slow-movers (inf and art).
I only buy the amount of mechs needed to pair with existing tanks. If I buy new tanks, which is rare for me in P2V, I usually do it together with the mech-combo.
This is actually one of the huge differences to OOB/BM3. Germany can’t afford a mech-spam and mech only really shine together with tanks. I think this solution is quite a beauty.
Anyway, Germany really needs to get swift control over Leningrad and Ukraine, with priority to the former because of the NO and highly strategic position.
When this goal is accomplished there should be enough force to keep on pushing and Germany may start to invest in fleet and land to protect the western front.
With Japan I usually try in the early game to contain China and grabbing key objectives, like the DEI and FIC (great place for a mIC and ab). In P2V it’s also lucrative to go after other islands, but Japan is hard pressed to do so early on, so it’s more for the mid-game if the previous expansion has been successful.
Islands are much more susceptible to counter-attacks and Japan can more or less trap the US into losing their valuable land-units when grabbing i e the Carolines on the cheap. Without pesky land threatening islands, Japan can breathe a lot more easily.
Carriers and des is the main early build. I usually go with 1 mIC in Shantung and 2 tr as the opening-build.
I also don’t care squat about the northern russians. If Russia DOWs, Japan will start to adjust to a northern conflict, but will be happy enough if Russia abstains. The southern objectives are so much more important.