It is not known to evolve into or from any other Pokémon.
Smeargle is best known for its ability to use the move Sketch, which permanently copies the last move used by the opponent. Due to this, it can legitimately have any move in the Pokémon games except for Chatter, and it can pass on any Egg move to Pokémon in the Field Egg group.
Smeargle are beagle-like, bipedal white and brown Pokémon that seem unremarkable at first, but they possess a long tail with an end that resembles a paintbrush. This paintbrush oozes with paint, and the color of the paint is apparently different for each Smeargle. Although sprites from the game depict green, brown and red, the anime also shows yellow and blue. It's been implied that each Smeargle has a different colored tail.
Smeargle each have a footprint on their backs that have the same color as the tail-tip. Smeargle also have a round structure on their heads with a point that resembles a beret in shape, with floppy, brown colored ears and a brown colored ‘collar’ on their necks. The rings encircling a Smeargle’s eyes are also brown, as are Smeargle’s eyelids. Their arms have two brown bands, and their legs only one, and each of the limbs have three digits, the fingers apparently being dexterous.
Smeargle secretes a fluid from its tail, which can be used as paint. Smeargle is the only Pokémon known to express itself in an artistic fashion. Smeargle is also the only Pokémon that can learn nearly any move permanently (with the exception of Struggle and Chatter) thanks to its signature move, Sketch.
Smeargle live in groups. When a Smeargle reaches adulthood, the other members of the group draw a paw-print pattern on its back. Those who refuse to let themselves be marked are ostracized from the pack.
Smeargle are very adaptable, and can live just about anywhere. One can always tell when a Smeargle's territory is found because it will mark the boundary with the paint-like substance excreted by its tail.