Dark does ×½ to Fairy

Generations VI to IX, single types. The other way round, Fairy against Dark, is ×2.

69 Dark and 64 Fairy species among the 1025 this site covers.

Attacker, Dragon and Dark Roaring Moon sprite

damage×½Generations VI to IX

Defender, Fairy Florges sprite

Florges #0671

Dark and Fairy did not exist in Generation I and Generations II to V, so Dark against Fairy has no value there.

Strongest Dark attackers

Roaring Moon leads Dark at Atk 139

Sturdiest Fairy defenders

Dual types that change the answer