Which two games began Pokémon’s second generation?

Pokémon Gold and Silver began Pokémon’s second generation of main-series games.

They were released in Japan for the Game Boy Color in 1999 and expanded the series beyond the original Kanto adventure. The games introduced the Johto region, 100 new Pokémon, a day-and-night cycle, breeding, held items, Pokémon genders, and new Dark- and Steel-type species.

Gold and Silver also connected back to the first generation. After completing the Johto storyline, players could revisit Kanto, where many locations and Gym Leaders from the earlier games appeared in updated form. This made the games function as both a new journey and a sequel.

Pokémon Crystal followed as an enhanced version, adding features such as the choice of a female player character and an expanded role for Suicune. Later generations began with Ruby and Sapphire, Diamond and Pearl, and Black and White, so those pairs are not correct answers for Generation II.