Pokédex/Anime/Pokémon Origins

The Kanto Pokédex appeared during the Pokémon Origins miniseries, where they served the same purpose as in the original games. They recorded basic info of any Pokémon encountered, and detailed info of any Pokémon caught. Much like in the games, one was given to both and  by Professor Oak. By the end of the last episode of the miniseries, Red had managed to capture all 150 Generation I Pokémon, excluding only. Blue's Pokédex was later crushed when his accidentally crashed onto it while he was battling  in the Cerulean Cave.

Besides listing all the caught Pokémon in numerical order, the Pokédex was also able to sort the recorded Pokémon data by other factors, such as the type, as seen when Professor Oak tried to identify the Pokémon Blue had fought by going through the list of Pokémon in Red's Pokédex.