The only issue I see with axis in team games is that they have the most and the best AT units.
Is a pain to play against a faction that, except a couple of pure AI units, everything else can do a lot of damage to your vehicles. In teamgames that makes easier for one of the players to spam Elite AI units to cap, push and harass. And each day they got more and more infiltration elite units (Falls, Jeager, Stormtroopers...), which makes the harassing even worse for allies.
I'm tired of seeing OKW players with 3 cheaper panzerschrecks bulletins stacked because he just needs that to fight allied armor until King Tiger/Jadgtiger arrives.
That makes me remember old vCoH times when in teamgames one player spammed just paks+tanks and the other snipers + vet3 Knight Cross Holders.
Allied AT capabilities should increase. USF zooks should be better, and soviets should have anything better than Guards/Cons against vehicles which currently both are pushed out of the meta due to their terrible AI abilities against OKW elite infantry.
The US' lack of AT is one of their core issues in team games aside from the lack of a late-game presence). I know bunker spamming is a newbie tactic but it actually becomes a problem in team games when you can't smoke past it because your opponent has a buddy who can make up for the MP loss by setting up supporting units in the vicinity. Meanwhile, unlike the Soviets, the US has no way of busting bunkers until they spend a fair amount of fuel and get the captain/AT gun. It often results in the US player/s being denied a large portion of the map for an unreasonable amount of time.
The other major issue involving AT is the construction of the US tech tree in general. In 1v1s it's easy to make a decision between the LT and Captain based on your opponent's tech. In team games, though, it's difficult to make a decision because your opponents could easily go in two different directions. If you go LT and one of your opponents goes armour, you can easily be forced off the map then and there. Same applies to Captain vs a large inf blob.
Obviously, these issues are partially nullified by simply rolling with a Soviet team-mate. That being said, God help you if you get stuck with double US.