say im using brainiac 5 who has outwit and perplex. i put bt on him, now with him being a wildcard can i perplex anyone on the team or do i have to pick a team that turn to perplex.

Only one team on one turn. You can pick which team he is on before you use Perplex and BT.

I was pondering the same question earlier today(Dr.Doom). My impression is that you must be able to use BT even though you do not have a real TA('only' WC). BUT in order to find which teammates you can perplex up you must declare a 'real' TA for your WC that is also shared by all the perplex recipients. You can not just perplex up your fellow x-man and Avenger because you yourself has BT on a WC-figure. You have to take a stand and choose one of them TA's.