From Bulbapedia, the community-driven Pokémon encyclopedia.

A Fisher or Fisherman (Japanese: つりびと Fisherman) is a type of Pokémon trainer that first debuted in the Generation I games. They are middle-aged men with rods, reels, and fishing gear. They were known as Fishers in Generation II but other than that they are known as Fishermen.

In the Japanese versions of the game, they are depicted as smoking, as fishermen smoking is a common stereotype in Japan. In the American versions, however, the cigarette has been removed, presumably because the Pokémon franchise targets a younger audience in America.

They specialize in Water-type Pokémon that can be caught via fishing.

In the TCG

A Fisherman character appears on its own titular card in the Skyridge expansion of the TCG.

Appearance

Fisherman Sprites

Image from Pokémon Red and Blue

Image from Pokémon Gold and Silver

Image from Pokémon Ruby and Sapphire

Image from Pokémon FireRed and LeafGreen

Image from Pokémon Diamond and Pearl

Generation I-introduced trainer classes
Beauty | Biker | Bird Keeper | Black Belt | Boss | Bug Catcher | Burglar | Champion | Channeler | Cooltrainer Cue Ball | Elite Four | Engineer | Fisherman | Gambler | Gentleman | Hiker | Jr. Trainer♂ | Jr. Trainer♀ | Juggler Lass | Leader | PokéManiac | Trainer | Psychic | Rival | Rocker | Rocket | Sailor | Scientist Super Nerd | Swimmer | Tamer | Youngster
Beta classes
Chief | Pokémon Prof.