A great Pilates move for slimming the legs is called the Heel Beats.
Basically what you're going to do is you're going to lay down on your stomach, and you're going to keep your legs completely straight. You can put your hands in front of you or down by your sides, whatever feels most comfortable.
Basically you're going to lift your legs up and you're going to beat your heels together. Keep your legs straight. This is working the hamstrings and the glutes. And go slower. Take your time. You can even cross, more like scissors.
Keep your legs straight, point your toes, you're really going to feel the burn in the hamstrings and the glutes. Do this for 20 or 30 seconds. Rest. I would do about two to three sets. Do it again. Lift up. Keep your legs straight, squeeze the glutes, the hamstrings, you're going to feel the burn. Make sure to always keep your core tight. And rest.
There you go. It's another great Pilates move for slimming the legs.