Clefairy locations — where to catch

In Lumiose City (Legends: Z-A)

• Wild Zone 19 — Walk, Static Encounter

In Kitakami (Scarlet & Violet – The Teal Mask)

• Chilling Waterhead — Walk
• Crystal Pool — Walk
• Dreaded Den — Walk
• Infernal Pass — Walk
• Oni Mountain — Walk
• Oni's Maw — Walk
• Reveler's Road — Walk

In Hisui (Legends: Arceus)

• Fabled Spring — Walk

In Sinnoh (Diamond, Pearl & Platinum)

• Mt. Coronet — Walk
• Trophy Garden — Walk

In Johto & Kanto (HeartGold & SoulSilver)

• Johto Safari Zone — Walk
• Mt. Moon — Walk

In Kanto (FireRed & LeafGreen)

• Celadon City — Gift
• Mt. Moon — Walk

In Johto & Kanto (Gold, Silver & Crystal)

• Mt. Moon — Walk
• Route 3 — Walk
• Route 4 — Walk

In Kanto (Red, Blue & Yellow)

• Celadon City — Gift
• Mt. Moon — Walk

Other games (10)

• Brilliant Diamond / Shining Pearl (Gen 8): Mt. Coronet, Trophy Garden
• Sword / Shield — The Isle of Armor (Gen 8): Ballimere Lake, Fields of Honor, Forest of Focus, Frigid Sea, Frostpoint Field, Giant's Bed, Insular Sea, Max Lair, Snowslide Slope, Soothing Wetlands, Tunnel to the Top
• Sword / Shield (Gen 8): Bridge Field, Giant's Cap, Hammerlocke Hills, Lake of Outrage, Motostoke Riverbank, Rolling Fields
• Let's Go, Pikachu! / Let's Go, Eevee! (Gen 7): Mt Moon
• Ultra Sun / Ultra Moon (Gen 7): Mount Hokulani
• Sun / Moon (Gen 7): Mount Hokulani
• Omega Ruby / Alpha Sapphire (Gen 6): Route 115, Meteor Falls
• X / Y (Gen 6): Friend Safari
• Black 2 / White 2 (Gen 5): Giant Chasm, Hidden Grotto
• Black / White (Gen 5): Giant Chasm

Clefairy — full Pokédex entry