Well, Onion is a green swordtail for sure. Comes close to one of the wild Xiphophorus helleris there are in the wild. But X.helleri group knows a number of subspecies and together with all the subspecies of the Clemenciae group they do belong to the socalled southern swordtails. Northern swordtails ain´t X.helleri.
Dominant male green swordtails tend to show the red on the lower part of the body. But this can also happen to an aquarium strain of the X.helleri. But yours does come close phenotypically to a wild version of the green swordtails.
But I do have molly issues since yesterday, one of my females is shimmying, but I think its because of the cold water and I don't have a heater yet 
