The second generation of Pokémon added 100 new species to the series.
These Pokémon debuted in Pokémon Gold and Silver, which were first released in Japan in 1999 for the Game Boy Color. The new species began with Chikorita and ended with Celebi in National Pokédex order.
Adding 100 species raised the total from the original 151 to 251. The games also introduced the Johto region, while allowing players to return to Kanto after completing the main Johto adventure. This made the second generation unusually connected to the first.
Generation II added more than creatures. It introduced a day-and-night system, Pokémon breeding, held items, two new types—Dark and Steel—and a color-focused presentation. Pokémon Crystal later expanded the generation with additional story elements. The figure is sometimes confused with later-generation totals or with the number of species available in individual game versions, but 100 is the official count of new species introduced by Gold and Silver.