Duskull locations — where to catch

In Kitakami (Scarlet & Violet – The Teal Mask)

• Fellhorn Gorge — Walk
• Infernal Pass — Walk
• Kitakami Wilds — Walk
• Oni Mountain — Walk
• Paradise Barrens — Walk
• Timeless Woods — Walk
• Wistful Fields — Walk

In Hisui (Legends: Arceus)

• Arena's Approach — Walk
• Avalanche Slopes — Walk
• Deadwood Haunt — Walk
• Icebound Falls — Walk

In Sinnoh (Diamond, Pearl & Platinum)

• Lost Tower — Walk
• Route 209 — Walk
• Route 224 — Walk
• Turnback Cave — Walk

In Johto & Kanto (HeartGold & SoulSilver)

• Johto Safari Zone — Surf

In Hoenn (Ruby, Sapphire & Emerald)

• Mt. Pyre — Walk
• Route 121 — Walk
• Route 123 — Walk

Other games (4)

• Brilliant Diamond / Shining Pearl (Gen 8): Route 224
• Sword / Shield (Gen 8): Dusty Bowl, Route 6, Galar Route 6, Giant's Cap, Giant's Mirror, Giant's Seat, Motostoke Riverbank, South Lake Miloch, Stony Wilderness, Watchtower Ruins
• Omega Ruby / Alpha Sapphire (Gen 6): Mt. Pyre
• XD (Gen 3): Onbs

Duskull — full Pokédex entry