In the most recent Justice League Action short Firestorm and Superman fight Metallo during it Firestorm transform Metallos green Kryptonite core into pink Kryptonite which turns Superman into Superwoman (but with a male voice). There is an on screen transformation but seeing that the entire short is 2:30 Superman does not stay a woman for long. Link to the short is below. Transforamtion happens at the 1:35 mark
http://kimcartoon.me/Cartoon/Justice...olors?id=77565