Articuno is a large avian Pokémon with predominantly sky blue plumage and wings said to be made of ice. On its forehead is a crest that consists of three, darker blue rhombus-shaped feathers. It has circular red eyes, a short gray beak, and long, thin gray legs. Each foot has three forward-facing digits and one facing backward. On its chest is a mass of white, downy feathers. Its long, streamer-like tail is longer than its body and the same shade of blue as its crest.

Articuno has the power to control ice at will. When Articuno flaps its wings, it can chill the moisture in the air around it, making snow fall. It flies from icy mountain to icy mountain. According to legend, it appears before doomed travelers lost in icy regions. As seen in the anime, Articuno sometimes aids travelers and guides them to safety. Articuno lives in cold, isolated locations such as snowy mountains filled with permafrost. Articuno loves Articuno Treats made by Snacksworth, who once encountered and sang with it in the past.

Forms
Articuno has a regional form: Galarian Articuno.

In Galar, Articuno has a distinct appearance. Its main body has lavender coloration with a black marking covering its chest. Its feet are black with lavender talons. The three feathers of its crest, which are longer, fused, and folded to the back, have the same purple color as its beak and tail. Its eyes glow light blue, appear to be mostly closed, and are surrounded by a black, mask-like facial disc. When Articuno utilizes its psychic power, the entire mask glows the same color as its eyes, as do the white, feather-like blades of condensed psychic power at the edges of its wings.

Galarian Articuno keeps itself airborne with its psychic power, almost never having to use its wings for this purpose. Instead, the blades on its wings can be used to slice through iron as easily as paper. Its eyes can fire beams of psychic energy that leave its opponents stuck in place as if frozen solid — this is what earns this Pokémon the name of its Kantonian counterpart. It also has the ability to create mirages of itself in order to fool its opponent and escape. Its elegant and refined movements belie a cold and callous personality. It is constantly migrating around the world but can be found in the Crown Tundra once every few decades congregating with the other birds at the Dyna Tree to eat its fruits.

(Source: Bulbapedia)