I've played multiplayer.
It has the same issue with free for all that any battle game has... one player gets picked on at a time until it's a 2-player game.
Playing 'sworn enemy' works well.
I've only played 2 on 2 once. It was OK. It works better than free for all. Each team picked one player to focus on. The first team to lose a player ultimately lost, but it was closer than you might think due to setup that happened before the player fell.
When playing 2 VS 2, I recommend pooling life. I know this is not great thematically, but It makes for a much better game play then always beating on one guy. It makes for great team synergy also.