costume switch
Two or more characters wearing each other's default clothes; an outfit swap.
Never use this tag if there is only one character in the image who happens to wear another character's clothes or if one of the two characters in the image wears the other's clothes, but the other is still wearing his/her own clothes, especially one that is a duplicate of the cosplay; use cosplay instead, if that tag is absent. Cannot also be used on obvious switches covered across two images; make those parent and child posts instead.