Wooper locations — where to catch

In Paldea (Scarlet & Violet)

• Cascarrafa — Trade
• Poco Path — Walk
• South Province (Area Five) — Walk
• South Province (Area Four) — Walk
• South Province (Area One) — Walk

In Kitakami (Scarlet & Violet – The Teal Mask)

• Chilling Waterhead — Walk
• Fellhorn Gorge — Walk
• Kitakami Road — Walk
• Kitakami Wilds — Walk
• Mossfell Confluence — Walk
• Oni Mountain — Walk

In Sinnoh (Diamond, Pearl & Platinum)

• Great Marsh — Surf, Walk
• Route 212 — Surf, Walk

In Johto & Kanto (HeartGold & SoulSilver)

• Cliff Cave — Walk
• Cliff Edge Gate — Surf
• Johto Safari Zone — Surf, Walk
• Route 32 — Walk
• Route 47 — Surf, Walk
• Ruins of Alph — Surf
• Union Cave — Surf
• Violet City — Gift, Surf

In Hoenn (Ruby, Sapphire & Emerald)

• Safari Zone — Surf

In Sevii Islands (FireRed & LeafGreen)

• Four Island — Surf
• Icefall Cave — Surf
• Ruin Valley — Surf, Walk

In Johto & Kanto (Gold, Silver & Crystal)

• Route 32 — Walk
• Ruins of Alph — Surf, Walk
• Union Cave — Surf, Walk

Other games (7)

• Brilliant Diamond / Shining Pearl (Gen 8): Great Marsh, Route 212
• Sword / Shield — The Isle of Armor (Gen 8): Soothing Wetlands
• Sword / Shield (Gen 8): Dusty Bowl, Giant's Cap, Giant's Seat, Rolling Fields, South Lake Miloch, West Lake Axewell
• X / Y (Gen 6): Friend Safari
• Black / White (Gen 5): White Forest
• HeartGold / SoulSilver (Gen 4): Primo
• XD (Gen 3): Pokespot

Wooper — full Pokédex entry