Gulpin locations — where to catch

In Paldea (Scarlet & Violet)

• East Province (Area One) — Walk
• South Province (Area Five) — Walk
• South Province (Area Three) — Walk

In Sinnoh (Diamond, Pearl & Platinum)

• Great Marsh — Walk

In Johto & Kanto (HeartGold & SoulSilver)

• Route 3 — Walk

In Hoenn (Ruby, Sapphire & Emerald)

• Route 110 — Walk

Other games (4)

• Brilliant Diamond / Shining Pearl (Gen 8): Great Marsh
• Omega Ruby / Alpha Sapphire (Gen 6): Route 110
• X / Y (Gen 6): Kalos Route 5
• XD (Gen 3): Cipher Lab

Gulpin — full Pokédex entry