In Driftveil city there's a guy that says ''if you find 50 Pokemon (on my pokedex)I'll give you something does anyone know what it is?
In B/W, you can get a Shell Bell from the man if you have 50 entries in the Pokedex. However, on B/W 2, it will require 70.
Source: Bulbapedia's page on Driftveil City.
