different types of joints, bones and muscles. Like bones that are the default but also ones that are rigid, bendy/squishy, and stretchy or bones that are lighter(like hollow bones) or bones that are heavier. Joints that are the default, ones that can only bend so much, ones that dont bend at all(to have more places for muscle) or joints that add friction to a creature(to have on feet but not on tails so they don't get stuck). Muscles that are the default, ones that are faster at expanding/contracting(More hyper in a way), and ones that are stronger than normal(for things like legs so they can hold themselves up easier).