Castform is a small, grayish Pokémon that resembles a cloud. Castform appears to have a pair of white goggles; however, Castform's appearance (and type) can change depending on the weather.
In strong sunlight, Castform's lower half becomes pure white while the head turns orange with smaller orange balls surrounding it. This gives Castform's head a shape that is similar to the sun.
During rain, Castform's lower half becomes a darker shade of gray. The head is blue, resembling a drop of rain.
In hail or snowy weather, Castform's head turns purplish-blue. The rest of of the body changes into a greenish tornado.
Gender differences
None.
Special abilities
Castform has the aforementioned ability to change its form with the weather (even though it lacks forms for sandstorms and fog). Castform is capable of various Fire-, Water-, Ice-, Electric- and Template:Type2 moves. Castform is one of only two Pokémon that can learn Weather Ball (the other is Roserade).
Castform borrows the power of nature to transform itself into guises of the sun, rain clouds, and snow clouds. This Pokémon's feelings change with the weather.
When Castform undergoes a weather-based transformation, the graphical interlude is the same as that of a Pokémon using the move Transform.
Castform will not transform in fog or during a sandstorm.
Castform's Weather Ball will always receive STAB, even when its form is changed, except in a sandstorm.
Castform's weather-based transformations are the same color whether or not it is shiny.
Origin
It appears to be intended to resemble and act like a living cloud. Its ability to change shape and type depending on the weather condition makes similar to a weather balloon.
Name origin
Castform's name seems to be a combination of forecast, predict the weather, and transform, referring to its ability to change type depending on the weather. The German and French names refer to this also. Its Japanese name may be a combination of 天気予報 tenkyohō, weather forecast, and 変わる kawaru, to change or transform.
This Pokémon article is part of Project Pokédex, a Bulbapedia project that aims to write comprehensive articles on each Pokémon species, as well as Pokémon groups and forms.