An alternate universe where everyone is now the opposite gender.
Or option 2; you wake up as the opposite gender. In fact, everyone is! You try to tell everyone that something is wrong but they all think everything is normal. What do you do?
Meet your new teammates:
Toni Stark
Stephanie Rogers
Nathaniel Romanoff
Samantha Wilson
Clarissa Barton
Fem!Thor
Fem!Loki