Here is the full list of all 20 It Takes Two achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
You did it! CO-LLA-BO-RATION!
You reached a higher state of mind. Or at least some peace and quiet.
Release that tension at the root level.
Don't feed the animals! Or do, they're adorable.
Breathe some wind into your ocarina, my skyward princess!
Helltower? More like hello-from-up-here-tower!
Choo Choo!
Now look who's extinct!
Guess it was time to cash out.
Put on a show and die trying.
Shoot for the stars, literally.
They had no way out.
Self-inflicted paparazzi.
It takes two to… torture.
All minigames found!
The truth was out there all along!
Isn't it pretty? That's going on the fridge.
Again? Keep track of your kids!
Took things a bit too far, didn't you?
Scurvy! Ye look smashing, captain!