Zubat
The Bat Pokémon
Type: Poison/Flying
Official Registration #: 41
Entry: A two-foot-tall eyeless, cave-dwelling bat known for detecting its prey using echolocation and, upon alighting on said prey, latching onto it with inch-long fangs and draining its very life force from its body. Also, given the prevalence of tunnels and caves in every region, at least half of the reason why this writer neither envies trainers nor desires to be one ever again.

Golbat
The Bat Pokémon
Type: Poison/Flying
Official Registration #: 42
Entry: The evolved form of zubat, by battle experience. Travel to deeper caves with larger zubat nests, and you may encounter its evolution, which is little more than a flying mouth full of void and fangs. Those of you who plan on traveling through the Kantonian league circuit should rest assured that golbat only feed on blood until absolutely full, and at that point, they become too lethargic to continue chasing down prey. Also, they are the third most common cave-dwelling pokémon in Kanto, right behind their pre-evolved forms and living boulders.

Crobat
The Bat Pokémon
Type: Poison/Flying
Official Registration #: 169
Entry: The evolved form of golbat, in response to closeness with its trainer. Arguably one of the easier evolutions-by-closeness to achieve, as zubat and golbat, when caught, are typically both astounded and thrilled to find themselves not simply electrocuted or buried under a pile of boulders on a cave floor. As such, despite the fact that it is not exactly famous for it, crobat are notably loyal and protective of their trainers. Which, really, is a good thing, as evolution gives them an extra pair of wings and a growth spurt that enable them to become one of the fastest, stealthiest, and largest flying predators in the pokémon kingdom, and its healthy diet of blood, naturally, never changes.