Doubles mechanics allow you to target two Pokémon at once, use spread moves, and Protect, which adds the necessary layers of skill to make the format viable.
Click on a friend's name and select the Multi Random Battle format from the dropdown menu.
As of now, there is no official ladder for Multi Battles; they are played for fun through direct challenges or unrated searches. The "2v2 Doubles" Competitive Format
Here is how to find a game:
Note: True (four humans, each controlling one trainer) isn’t possible — it’s always one human controlling both Pokémon on their side of the field.