I think I figured out how a 2v2 would work for Air Poker, if it isn't separate matches.
Lalo this chapter said that the best hand thing was only his theory and he has other possibilities to consider. When Kaji implied that his best hands was a theory, I thought about other possibilities in the sense of the deck being shuffled and the first realistic hand being used, or the referees deciding off the top of their heads, so without the guarantee of it being the best, but whatever comes to mind first. When Lalo brought it up this time, it hit me that Hal and Fukurou could be the ones deciding, instead of the referees. If your theory is right, I think that's how the 2v2 is being performed. What this changes from the best hand though, I'm not sure. I doubt either Hal or Fukurou would mess up the hands... unless Hal loses his memory mid match.