• since the characters will then belong to the person who buys it
then yes, they can use them in any way they want to.
as for the outfits. SOME artists only sell it like I am. One outfit. One character.
OTHERS. make more clothes and sell those with the character. (One character, 2-3 or more outfits for said character)
SOME OTHERS. sell the character and the outfits separately.
and SOME SOME OTHERS sell only outfits.