Where to catch Golduck

In Paldea (Scarlet & Violet)

• Area Zero — Walk
• Casseroya Lake — Walk
• Glaseado Mountain — Walk
• North Province (Area One) — Walk
• North Province (Area Three) — Walk
• South Province (Area Four) — Walk, Static Encounter
• South Province (Area Six) — Walk

In Hoenn (Ruby, Sapphire & Emerald)

• Safari Zone — Surf

In Johto & Kanto (Gold, Silver & Crystal)

• Ilex Forest — Surf
• Mt. Silver Cave — Surf, Walk
• Route 35 — Surf
• Route 6 — Surf

In Kanto (Red, Blue & Yellow)

• Route 6 — Surf
• Seafoam Islands — Walk

Golduck — full Pokédex entry