Wild Pokémon are Pokémon that have not yet been captured by a trainer. This is one of the only methods of obtaining a Shiny Pokémon. The player must capture the Wild Pokémon found in routes to fill up his/her Pokédex and to advance in his/her adventure. In the first episode of the anime, the Pokédex told Ash that wild Pokémon are jealous of Pokémon trained by humans.
Some wild Pokémon can only be found in a certain condition. For example, the Pokémon, Audino, can only be found in shaking bushes.