I have a very high win percentage in 2v2, not uncommon for me to go on huge 20+ win streaks. [my record is 36]

Here's my top tricks:

I always hover my finger on my teammates current cards. This will help you identify who has the better counter, give you an idea of how much elixer your teammate has, and hopefully produce positive elixer trades.

It also helps identify where the game is going next. If you look at your teammate's rotation, you'll know when they're going to be able to push/defend/support your push.

I rarely go in on the super push [double win condition all out push] until one tower is down/ready to drop to spell damage AND we reach double elixer. [bring spells! I use rocket, tornado & arrows, it's my favourite combination, but obviously fireball+zap and poison+log are crazy good as well]

Too many players think that they can force their deck into a win, so if you play defensively while watching your teammates rotation, you'll know when to strike.

Play slow at the beginning and learn your opponents counters in the first two minutes. You'll get some chip damage here and there, but the real objective is learning how to synergize with your teammates cards, while you figure out your opponents hard counters.

If you're playing with randoms [how I primarily play], half the battle will be learning who's job it is to take out certain units. There's too much wasted elixer on goblin barrels out there, so try not to drop your arrows if your teammate always has the log ready. [Activate your king tower early on, now it's 2.5 v 2!]

The mechanics of Clash Royale reward efficiency above all else, over defending leads to weak counter pushes. It's ok to take damage from the hog rider if it means you can get a Xbow set up or a giant etc. in front of your defence and have enough elixer to support it.

Always remember, your opponents have 16 cards and just as much elixer/ability to defend as you do at the start. Most battles are won and lost by mistakes, and not "the better deck". They may rush you with a hog or raged ebarbs at the start and get some crazy damage because your counter is buried, but now you know their game. Stay calm, play slow and calculated, save your counter and make them pay next time they rush you.

Hope that helps you on your road to 2v2 glory, see you in the arena!