The starting rule is;
Entire team. I don't mind if a teams have 25 players, but there should be a max. of x2 6*
But;
Exist the option, "if one really wanna keep a good player, so don't sell it just cause reached the 6*" to declare it as a inactive one, so, then he should be with the reserves and can not be used in any other match.
I'll be flexible.