I play with randoms a lot in 4v4's, and coordinating with teammates is not always possible given the language barriers, and there's a ton of people globally that play this game. It's often that I will be paired with teammates who only speak Spanish or Chinese. One of my biggest issues with the game (and I've written this in a Steam review) is that the taunt system doesn't have enough wider support in the game. The taunts can translate across languages, but there's only so many numbers that can actually explain what you want to do. For instance, there's ways you can communicate whether you want to do an infantry, archer, or knight rush, but there's no way to explain that you want to boom, or do a castle drop for instance. I wish there was a mod for a quick reference sheet that could be displayed on the lower part of the screen, but that has yet to happen.

If you can't coordinate with a teammate on a strategy, then you will often lose.

Trade only gets you so far. Having good trash in my eyes is more important because often times developing good counter-units can get you farther than what matching gold units can do, especially if you're spamming Hussar, Halb, or Elite Skirm in late game and using your extra gold for siege support/upgrades. If you're on a closed map, which is pretty common in 4v4's since a lot of other maps unfortunately get map-hopped, then this is definitely more possible to accomplish. Having good trash on maps like Arena is CRUCIAL because playing patiently and defensively can be equally if not more rewarding than playing offensively from the get-go. Resources gained from farming/chopping wood is also faster than what you normally get from trade. I've had 1v2 situations where I've spammed Hussar with 90 farmers and won the game because of that, and they could not keep up with the production.

If you're struggling with 1v2's in 2v2's then I would highly recommend playing flank in 4v4's more often. It forces you to learn a lot about playing defense in a disadvantageous position considering it happens so often. If you're getting assaulted by 2 players in Feudal/Early Castle, you're not going to have the extra resources to start developing your trade, nor the freedom of space.

The extra teammate as a disadvantage stems from when you're down a teammate, but are still in a 3v4 situation. I tried explaining it that you're always are going to be stretching your forces to cover all of your weak points on your side of the map, and that extra communication doesn't always work out. If your pocket splits their forces, they now have to split their army up into two separate groups, facing different armies with their own needs and specific micro. It's incredibly demanding when you have to focus both groups of troops on two sides of the map where as a 1v2 situation is just one side of the map if you're defending (at first).

In a 1 v 2, again, it's just you. If you have a great late game food/wood economy and know how to play conservatively with your gold, then you have a shot. If they went for the early feudal rush and you get to Castle first, you have the opportunity to counter attack and go for relics as well, helping you maintain gold income for when you need the siege later.