All you need is a medicine ball 6-8 lbs (also abbreviated as "med" for short) and wall you can bounce it at. Work each drill 2 sets of 8 reps and work up to 2 sets of 12 reps with a heavier ball.
– Smash Overhead Med. Ball. While standing tall, hold the med ball overhead with arms fully extending, quickly fire the ball toward the ground and as it rebounds, catch it at eye level. Extend arms overhead again and repeat. Keep arms fully extending to stretch lasts. As you follow through on the throw, think of a swimmer's stroke into the ground. Avoid bending at the hips.
– Front Throw Med Cross. While standing about 5 feet away from wall, cradle the med ball in both hands, facing the wall. Now rotate the core and shoulders to your left side into "load posture". Explosively toss the med ball underhand against the wall. As you catch the rebound, decelerate it and rotate core to right. Repeat in an alternating fashion. Key points: Keep all rotation coming from the hips and up. Focus on increasing elasticity; avoid shoulder dipping while in the rotation phase.
– Chest Pass Med Ball. While standing about 3 to 5 feet from the wall, facing directly, hold the med ball with both hands. Explosively pass the ball against the wall around chest height. Catch it and repeat. Key points: concentrate on rapid, explosive throws. Keep abs engaged and avoid extra movements in the lower body. Decelerate ball on the rebound.
You can strengthen the upper body chain for all types of sports like basketball and baseball. These moves are also great for the core stability.