Since Luffy can twist and contort his body in any way he can imagine thanks to his Devil Fruit, it means he can get extra creative when assuming a new form that enhances his strength and durability in a fight. It's always a huge moment in the anime and manga community when Luffy unleashes a brand-new form. But while it's easy to initially focus on their strength and new abilities, their designs also go a long way in making these transformations memorable and unique.