The core series of the Pokémon games or core games, commonly referred to as the main series or mainline games by fans, is the game series that is always Classification · Content model · List of core series games · Timeline. It's hard to keep track of all Pokémon releases, but we did our best in cataloguing each of the franchise's most notable games. Check out. Pokémon is a series of video games developed by Game Freak and Creatures Inc. and published by Nintendo as part of the Pokémon media franchise. First released in in Japan for the Game Boy, the main series of First release : Pokémon Red and Blue ; February.