Here are two exercises I use with clients when they start to turn the corner on their functional movement. When i start noticing good stability coming through the thoracic spine (mid-upper-back) and lumbo-pelvic region (lower back/hip), I usually throw these to exercises at them. They are great for the development of your inner and outer unit core systems.
1.) Medicine Ball pushup isometric hold – This exercise is going to engage the pectoral muscles, along with an isometric engagement of all your core systems. Be sure to set your hips into a posterior tilt in order to get proper hip/core stability.
2.) One Arm Medicine Ball Throw – Great for the development of your transverse plane muscle systems. Be sure to stagger your stance and make the movement as fluid as possible.