It really just depends on what skill she has when you retire her...usually I either get a blue speed skill or a red toughness skill. In the case of the blue speed skill, you would need a stallion with a pink music note (?) skill. In the case of a red toughness skill, you would need a yellow dynamite skill (most of the time, Shady Sun will carry this skill, and I've successfully bred an excellent baby out of those two).