Medicine ball presses will help work your shoulder function and help maintain body position from the medicine ball movements.
You can either do a rotational press or stepped rotational press with the medicine ball, just make sure your tail hand is ready to press through. This is a different way to create force, will work your shoulders, create more stability and the ability to create more force.
Another medicine ball workout is kneeling chest to wall press. This will work your core, your upper body, and is all about repetition.
Doing both presses and rotational slams will help with balance, stability, and force creation making your body more efficient.