I'd probably do a XC medallion. The stud is strongest in Mv and Int so I don't see a need for a D boost. XC would cover the stud's Str weakness as well as Spd, his second weakest trait, neither of which your girl is strongest in. It's Hrt boost also won't hurt considering that's one of your girl's weakest two traits, and not one of the stud's strongest two.