Where to catch Clefairy

In Kitakami (Scarlet & Violet – The Teal Mask)

• Crystal Pool — Walk
• Infernal Pass — Walk
• Kitakami Hall — Walk
• Oni's Maw — Walk
• Reveler's Road — Walk

In Johto & Kanto (Gold, Silver & Crystal)

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

In Kanto (Red, Blue & Yellow)

• Celadon City — Walk
• Mt. Moon — Walk

Clefairy — full Pokédex entry