Butterfree resembles a vaguely anthropomorphic butterfly. Unlike true insects, it only has four legs, which are a pale blue color. It has a nose-like structure which is a similar color. Its body’s coloration is a darker purple-blue. It has large veined wings which are white with black markings, in very rare cases individuals may be born with pinkish coloration. The markings can help distinguish male and female individuals. It has large compound eyes which tend to be a reddish color. Like members of the order Lepidoptera, Butterfree’s wings are covered in fine scales. Its legs are covered in fine hairs which aid in the collection of honey.
A female has black spots on the lower parts of her wings.
The waterproof scales on Butterfree’s wings are loosely attached, and if the Butterfree flaps them hard enough, they will be released into the air. This resulting “dust” is toxic, and can be irritating if inhaled.
Butterfree spends most of its time foraging for nectar and pollen from flowers. In the wild they need to eat constantly. Special adaptations such as waterproofing on their wings, and tiny hairs on their legs let them gather food even in the rain. Butterfree will roam up to six miles from their nest in search of honey. During breeding season, Butterfree take to the air en-masse. Female Butterfree generally choose their mates on the basis of performed aerial aerobics, however other factors may come into play. In order to mate, male Butterfree appeal to a female Butterfree they wish to mate with by performing the courtship dance. If the female is receptive she will also reciprocate by joining in performing the courtship dance to the other male Butterfree as he also continues to "dance".
Butterfree can be found in forests and wooded areas with high amounts of moisture and mist. They can also sometimes be found flying near the ocean, which may be part of their migratory breeding pattern.
In Pokémon Special, Yellow has a Butterfree which evolved from a Caterpie she befriended and captured. Her uncle, Fisherman Wilton, also has a Butterfree. Both of them are able to use Butterfree as a mode of flight, using Butterfree to hold onto their backs as they fly.
| colspan="13" | Bold indicates a move that gets STAB Italic indicates a move that gets STAB only from an evolution of this Pokémon A colored initial indicates that the move is not available to be tutored in this game, while a colored background indicates that the move is available.
Butterfree is the first Pokémon shown in the anime to have an alternate color. However, this alternate color was pink, which is not the same as the alternate color of Butterfree in the games, in which only its wings, feet, hands, and mouth are pink.