are team abilities optional

example could I choose to unstealth via kabuki or bat team to get perplex effects and then turn it back on

Team abilities are optional and act the same way as optional powers. You can turn them off but you can not turn them back on. Once turned off, they remain off for the remainder of the current turn. So, if you turned off the Batman Ally TA during your turn it would stay off for the remainder of your turn and it comes back on automatically at the end of the turn. In this case, you'd be left open to your opponent's PCers but it would come back on before your opponent could attack you.