Where to catch Poliwag

In Kitakami (Scarlet & Violet – The Teal Mask)

• Fellhorn Gorge — Walk
• Kitakami Road — Walk
• Mossfell Confluence — Walk
• Reveler's Road — Walk

In Johto & Kanto (Gold, Silver & Crystal)

• Blackthorn City — Good Rod, Old Rod, Super Rod, Surf, Walk
• Ecruteak City — Good Rod, Old Rod, Super Rod, Surf
• Ilex Forest — Good Rod, Old Rod, Super Rod
• Mt. Silver — Surf
• Route 22 — Good Rod, Old Rod, Super Rod, Surf, Walk
• Route 28 — Good Rod, Old Rod, Super Rod, Surf
• Route 30 — Good Rod, Old Rod, Super Rod, Surf, Walk
• Route 31 — Good Rod, Old Rod, Super Rod, Surf, Walk
• Route 35 — Good Rod, Old Rod, Super Rod
• Route 43 — Good Rod, Old Rod, Super Rod
• Route 44 — Good Rod, Old Rod, Super Rod, Surf, Walk
• Route 6 — Good Rod, Old Rod, Super Rod
• Ruins of Alph — Old Rod
• Violet City — Good Rod, Old Rod, Super Rod, Surf
• Viridian City — Surf

In Kanto (Red, Blue & Yellow)

• Celadon City — Good Rod
• Cerulean Cave — Good Rod
• Cerulean City — Good Rod
• Cinnabar Island — Good Rod, Super Rod, Walk
• Fuchsia City — Good Rod
• Indigo Plateau — Good Rod
• Pallet Town — Good Rod, Super Rod
• Route 10 — Good Rod
• Route 11 — Good Rod
• Route 12 — Good Rod
• Route 13 — Good Rod
• Route 17 — Good Rod
• Route 18 — Good Rod
• Route 22 — Good Rod, Super Rod
• Route 23 — Good Rod, Super Rod
• Route 24 — Good Rod
• Route 25 — Good Rod
• Route 6 — Good Rod
• Safari Zone — Good Rod
• Sea Route 19 — Good Rod
• Sea Route 20 — Good Rod
• Sea Route 21 — Good Rod
• Seafoam Islands — Good Rod
• Vermilion City — Good Rod
• Viridian City — Good Rod, Super Rod

Poliwag — full Pokédex entry