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Castform is an artificial Pokémon that changes appearance and attitude based on the weather. Its body is made of cells exactly like those of water molecules, causing its cellular structure to be altered by temperature and humidity. It uses this ability to protect its tiny body. In its Normal Form, it resembles a plain, gray cloud with a single wisp extending from the top of its head. When in its Sunny Form, its lower half becomes pure white, while the head turns orange has develops small orange spheres around it. This gives it the overall appearance of the sun above a small cloud. While in its Rain Form, it will have a dark gray lower half resembling a storm cloud. The head will be blue and resemble a raindrop. In its Snowy Form, its head turns purplish-blue. The rest of the body changes into the shape of a mint green, cumulonimbus cloud. Regardless of the form it takes, it will always have a large, spherical head and a lighter colored mask-like marking over its eyes. Aside from its various forms, Castform is able to utilize weather powers in the form of its previously signature move, Weather Ball. Despite its manmade origins, it can be found in grassland areas.