As far as 2v2 go, I'm a huge believer in having to play as Ost + OKW. Double OKW simply will not cut it against a proper Allied team. Ost + OKW can beat USF + USF or USF + Sov or Sov + Sov, but I'm not going to lie... the fight is definitely up-hill.
Double USF is probably the easiest. As OKW you should open with a Puma while your partner goes something like: MG, Sniper, Gren. Depending on your skill/level and coordination you can mix up this build but Snipers are absolutely devastating against USF - especially when back up by a Puma (to protect from M15/M20/Stuart). Basically you want to use your Volks as meatshields to spot for the Ost Sniper/MG42. After this the Ost player should work their way to something along the lines of:
3x Gren, 2x MG, 1x Sniper, 2x PaK + 251. The 251 is twice as strong in team games because you can both reinforce from it. The late game goal is a Tiger, so they should be playing either Assault Support, Lightning War, or Spearhead.
As the OKW player you can pick up Fusiliers, which make a really great combo with LMG grens. LMGs rock at long range, Fusiliers shred at short range. This is probably the most boring play-style because you'll build repair truck, heal truck and then nothing else with fuel until your Jagdtiger. Alternatively you could go for JLI so that you have infiltration nades + an Ostwind (your partner will probably not be teching T3). I don't really like the idea of fortifications against double USF because their tanks are squishy and slippery, the PAK43 won't be nearly as strong as it would be against IS2s, T34/85s, KV tanks, etc. Generally I still play Luftwaffe because I hate playing without MG34s. Fallshirms are amazing in the right situations and now that OKW gets 100% munitions the valiant assault ability can be downright amazing.
Anyways, as the OKW player you're a lot more free on your commander choice. You won't really *need* the JT against USF, because they don't have anything like the KV-2 or ISU-152, but it is still solid. Your primary goal as Ost + OKW vs double USF is to make it to the Tiger. A pair of PaK40s + Tiger is a nightmare for USF to deal with. You, as the OKW player, will secure the early game with your Puma - babysit that sniper and watch it do work. Mid-game you have to be flexible to figure out if you need some indirect fire (Stuka or IG), some mobile AT (Jp4, another Puma). With the sniper around, and access to so many good MGs, odds are you won't need much extra AI, but Obers are always very strong. Just make sure that, before spending 90 fuel on the flak HQ, you have enough AT in case E8s or other Shermans show up. Dual PaK40 + Jp4 combo is great when used in unison, and should allow you to get to that Tiger.
TL
R -
Ost should play T1/T2 into a Tiger. Snipers are amazing against USF, even more-so when backed up by a Puma. If you don't feel confident microing a sniper (well first I'd say to let yourself practice, but another Gren is fine). You will want a pair of PaK40s (they're the best AT gun in the game) and are extraordinarily potent against USF because all their tanks are so "squishy" and lightly armored.
OKW player should get a Puma and do everything in your power to support your Ost partner. You *need* to play as a team to cover each other's weaknesses. Use your Volks liberally. They will gain vet from taking damage, they're cheaper to reinforce than Grens, and they're just a lot more expendable in general - just make sure you don't lose any squads. Figure out what unit(s) will carry you into the Tiger and try to drag the game out. Jacksons are great against Tigers, but not when you have two PaK40s, 2-3 Schrecked Volks and probably a Jp4 around. All USF Sherman models just kind of suck against the Tiger.
Units I tend to avoid against double USF:
Luschs - (If you can catch them off-guard it can be strong, but a good USF team will get Lt + Capt, in which case your Lusch will get hard-countered by a Stuart or 57mm AT gun). *IF* you see double Lt, Luschs can be strong. Just make sure your ally builds a med bunker (they probably should be doing this anyways).
Sturmtiger - I hate this unit, imo it sucks, just get a Stuka.
IR HT - Unless the game is CRAZZZZY campy... why bother.
251 Flak - This patch this vehicle just kinda sucks... it will lose to the M15, it will lose to the Capt, it will lose to the 57mm and it will lose to the Stuart. Don't bother.
In my recent streams I've messed around with early Kubels but having your partner grab and MG42 is just way better. Kubel needs some love for 2v2.
Units I always build:
Volks (obviously)
Puma - my favorite unit, so good, much love.
Stuka - I always try to find a time/place to fit a Stuka in, the squad wipe potential is #RektCity status, plus USF players love to blob. Stuka loves shooting at blobs.
I'll generally round out my build with a Jp4, to back up the PAK40s and support the Tiger. I prefer the Jp4 over the Panther, in the current state of the game because they seem to stand up to Jacksons a bit better.
Wow, this ended up being super long. I'll try to get some one good to play some 2v2 with me this weekend and make a video or two or three. If anyone in the thread wants to play some games this weekend maybe we can find a time. I'm fine with playing as either Ost or OKW.