Professor Oak features in the RBY series of the Pokemon Manga.
He owns every non-legendary Pokemon that lives in the Kanto region.
Professor Oak gave Red and Green both a Pokedex each, Green obtained Charmander and Red received Bulbasaur.
After accidentally releasing all of Oaks’ Pokemon, Red sort out to help Oak. Hours later, Red and Oak re-captured all of the accidentally released pokemon, except one, Bulbasaur. After saving Red from a wild Machoke, Oak decided to give Red Bulbasaur.
Anime
In the anime Professor Oak is a famous scientist and poet pokémon, it was he who gave Ash Ketchum, when he turned 10 years old, his first Pokemon, Pikachu, and his grandson Gary Oak a Squirtle. May also gave a Squirtle baby.
Several of Ash’s Pokémon are in their lab, such as: