Q:
Is it possible to play online with multiple players per console ? e.g. two players on one Switch playing over the internet with two players playing both on another Switch.
A:
It is possible to play multiple local players online - however in the specific instance you mentioned, that's the only config of players (2v2) that the game doesn't currently support. Basically the host can have any number of local players but can only play against one player on a client machine. 2vs2 is something we're looking at right now however, hopefully we'll be able to support this in an update.