I’ve tried playing four square duos once, it didn’t end up too well. But at the same time, each four square is different.
Also, last year’s four square (for me) definitely had alliances and targeting (the former was allowed, the latter wasn’t but nobody enforced it) but this year’s four square doesn’t.
On the last day of 5th grade, the four square I played at the time (5th grade four square) merged with 4th grade four square. Since there were more 4th graders that played four square than 5th graders, fourth graders dominated the game. Their rule that we didn’t have is that you can’t do pass-backs. If my four square banned pass-backs, then everyone (especially me) would be out immediately.