Crobat

Crobat is a purple, bat-like Pokémon with a small, round body. It has long, pointed ears, yellow eyes with red pupils, and a small mouth that usually has its teeth bared. On its body are two pairs of wings: an upper pair that is slightly larger and a lower pair that developed from its legs. Both pairs have green-blue membranes, but the lower pair's membranes are only visible from the back. The upper wings have two claw-like fingers near the middle. On the bottom of its body are what appear to be a pair of stubby feet or tufts of fur.

Crobat is capable of flying long distances by alternating between its two sets of wings. The extra set of wings has also improved its flight speed without sacrificing its ability to fly silently. The combination of silent flight and sharp fangs allows it bite down on prey without being noticed and drain their blood. If unable to consume blood, it becomes lethargic and unable to fly. Due to its lack of legs, it is clumsy on the ground and only able to crawl around with its wings. Crobat is rarely found in the wild, though they are typically found in caves or on tree branches, where it hangs upside-down by its rear wings.

(Source: Bulbapedia)