Takeshi

Takeshi appeared primarily as an opponent to Satoshi in his debut episode; unlike later Gym Leaders, he requested to join Satoshi on his journey, aiming to be the world's greatest Pokémon Breeder.

Takeshi mainly provides an advisory role to the other main characters of the anime, being several years older than the rest of them. His knowledge of Pokémon battles is great, causing him to often referee matches between Satoshi and others. Takeshi also fancies himself as something of a ladies' man, though each time he hits on someone he is either rejected outright; pulled away by Kasumi or Masato; or, more recently, Poison Jabbed by his Gureggru.

(Source: Bulbapedia)