Generation II was released in 1999 (Japan) and 2000 (worldwide) with Pokémon Gold, Silver, and later Crystal. It expanded the Pokémon world with new features and the introduction of the Johto region.
Key Features
Region: Johto (with access to Kanto post-game)
Total Pokémon: 100 new, total 251
Games: Gold, Silver, Crystal
Introduced Day/Night cycle based on real-world time