Which two new Pokémon types did Gold and Silver introduce?

Pokémon Gold and Silver introduced the Dark and Steel types.

The two types debuted in the second generation of the main Pokémon games, which launched for the Game Boy Color in Japan in 1999. Their addition expanded the battle system beyond the original generation’s types.

Dark-type Pokémon and moves were designed to counter Psychic-type dominance, while Steel-type Pokémon added a heavily defensive typing with many resistances. The games also introduced new moves that used these types, giving Trainers more strategic options.

Gold and Silver added 100 new Pokémon, the Johto region, held items, breeding, and a real-time clock. Because the games also introduced many other mechanics, players sometimes remember the new types as later additions, but both Dark and Steel originated in this generation.