Have a formation list to place players on each team
For example if someone posts an 11 a side game, we would like to know immediately the position preference of the player just signed up to the game. So you can have a basic 442 formation and the player joining or the organiser can put that player in that position to that they know where they are going to play in advance and also have n idea of what type of players are missing from the game. Like if there is a lack of left backs or a lack of goalkeepers, so people will already know that they may have to rotate in that position. Same goes for smaller sided matches.