Fairy-type Pokémon are weak to Poison -type and Steel -type moves in the mainline games and in Pokémon GO.

Quick Scoop: Fairy Weaknesses

  • Takes super-effective damage from:
    • Poison-type moves 🧪
* Steel-type moves ⚙️
  • Resists: Fighting, Dark, Bug moves (they do reduced damage to Fairy).
  • Immune to: Dragon-type moves (they do no damage at all).

So if you’re facing a Fairy-type, bringing strong Poison or Steel attackers is the reliable way to knock it out fast.

Type chart snapshot (core games)
Against Fairy Pokémon Effect
Poison moves Super effective (2× damage)
Steel moves Super effective (2× damage)
Dragon moves No effect (0× damage)
Fighting, Dark, Bug moves Not very effective (½× damage)
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Fairy-types were added partly to check the dominance of Dragon-types, which is why they completely ignore Dragon moves and hit Dragons super effectively.

TL;DR:
If you’re asking “what is Fairy weak against,” the answer is Poison and Steel, in basically all current Pokémon games.

Information gathered from public forums or data available on the internet and portrayed here.