It flies so si lently through the dark on its four wings that it may not be noticed even when nearby.
The development of wings on its legs enables it to fly fast but also makes it tough to stop and rest.
As a result of its pursuit of faster, yet more silent flight, a new set of wings grew on its hind legs.
If this POKéMON is flying by fluttering only a pair of wings on either the forelegs or hind legs, it’s proof that CROBAT has been flying a long distance. It switches the wings it uses if it is tired.
CROBAT sneaks up on its intended prey using wings that barely make a sound. This POKéMON rests by hanging on a tree branch with its rear legs that serve as wings.
— Pokédex entries (via PokeAPI)