Pokémon Gold and Silver introduced 100 new Pokémon species.
Released in Japan in 1999 for the Game Boy Color, Gold and Silver formed the second generation of the main series. They expanded the Pokédex from the original 151 species to 251, adding creatures such as Chikorita, Cyndaquil, Totodile, Lugia, and Ho-Oh.
The games also added breeding, held items, a day-and-night cycle, Pokémon genders, and a real-time clock. Their setting, the Johto region, was connected to the earlier Kanto region, allowing players to revisit the original area after completing the main story. The 100 new species are separate from later Johto-related additions introduced through remakes or other generations.