Where to catch Vulpix

In Kitakami (Scarlet & Violet – The Teal Mask)

• Chilling Waterhead — Walk
• Crystal Pool — Walk
• Fellhorn Gorge — Walk
• Infernal Pass — Walk
• Kitakami Hall — Walk
• Kitakami Wilds — Walk
• Mossfell Confluence — Walk
• Oni Mountain — Walk
• Oni's Maw — Walk
• Paradise Barrens — Walk
• Reveler's Road — Walk, Static Encounter
• Timeless Woods — Walk
• Wistful Fields — Walk

In Blueberry Academy (Scarlet & Violet – The Indigo Disk)

• Chargestone Cavern — Walk
• Polar Biome — Walk

In Hoenn (Ruby, Sapphire & Emerald)

• Mt. Pyre — Walk

In Johto & Kanto (Gold, Silver & Crystal)

• Route 36 — Walk
• Route 37 — Walk
• Route 7 — Walk
• Route 8 — Walk

In Kanto (Red, Blue & Yellow)

• Celadon City — Walk
• Pokémon Mansion — Walk
• Route 7 — Walk
• Route 8 — Walk

Vulpix — full Pokédex entry