Dark was the new Pokémon type introduced in Generation II alongside Steel.
Both types debuted in Pokémon Gold and Silver, which began the second generation of the video game series. Their addition changed the battle system by creating new strengths, weaknesses, and strategic possibilities.
Dark-type Pokémon and moves were designed partly to balance the powerful Psychic type from the first generation. Steel added strong defensive properties and helped rebalance several existing matchups. Pokémon such as Umbreon represented the new Dark type, while Steelix and Skarmory showcased Steel.
A common mix-up is Fairy, which was introduced much later in Generation VI. Dragon was already present in Generation I through Dragon-type Pokémon and moves, although it had few representatives at the time. Ghost was also an original type. Generation II’s two additions were specifically Dark and Steel.