Crobat is the most bro-tier Pokemon to ever exist. Allow me to explain:
>Generation 1 was full of neverending Zubat
>Golbat wasn't very strong either, it had no decent moves and Wing Attack was super weak
>Gen 2 comes around
>You can find Dark Cave early if you explore thoroughly, like a good trainer should, and pick up a Zubat
>Sprout Tower immediately gives Zubat a place to shine
>By being willing to give Zubat another chance, you gain access to Bite, the first Dark type move you've ever seen
>This is the first time you even get to see anything of the two new types at all
>Dark was Special and Bite was no longer Normal type, so Zubat coild now chew through Rock Pokemon without a problem
>You can even teach it Steel Wing once you find the TM and have both new types represented
>Golbat rewards you again when it learns Wing Attack and you discover that it's much more powerful now
>Being a happiness evolution, you are rewarded even further for keeping it with you since it will evolve into Crobat almost immediately after becoming Golbat
>Then to cement its status as a bro among bros, it can then learn Fly as a Crobat for maximum comfort
>Even in competitive play Crobat can still hold its own by being one of the fastest motherfuckers in town and having an entire SkyMall catalog of status moves to pick from

Crobat is the epitome of a bro Pokemon because it continually pulls more weight than you had any reason to expect. After you have been conditioned to think of Zubat as a generic shitmon for years, it turns into an absolute badass if you give it a second chance to prove itself.