OLM produced the Pokémon television series beginning in 1997.
OLM, originally associated with the name Oriental Light and Magic, was commissioned to animate the television adaptation after the Pokémon games became successful. The studio’s work helped establish the bright, readable visual style that made Pokémon accessible to a worldwide children’s audience.
Kunihiko Yuyama served as the anime’s chief director for many years, while OLM handled the animation production. These are different roles: Yuyama was a director, whereas OLM was the studio responsible for producing the animated series. The first episode aired on TV Tokyo on April 1, 1997.
OLM also worked on Pokémon’s early theatrical films, including Pokémon: The First Movie. The studio’s long association with the franchise is one reason it is often identified with Pokémon anime history, even though later Pokémon productions also involved additional studios and production teams. The answer is the abbreviated studio name, not a network or distributor.