Gyarados locations — where to catch

In Lumiose City (Legends: Z-A)

• Wild Zone 11 — Walk
• Wild Zone 20 — Walk

In Paldea (Scarlet & Violet)

• Asado Desert — Walk
• Casseroya Lake — Walk, Static Encounter
• East Paldean Sea — Walk
• East Province (Area One) — Walk
• East Province (Area Two) — Walk
• Glaseado Mountain — Walk
• North Paldean Sea — Walk
• North Province (Area One) — Walk
• North Province (Area Three) — Walk
• Socarrat Trail — Walk
• South Paldean Sea — Walk
• South Province (Area Five) — Walk
• South Province (Area Six) — Walk
• West Paldean Sea — Walk
• West Province (Area One) — Walk
• West Province (Area Two) — Walk

In Kitakami (Scarlet & Violet – The Teal Mask)

• Fellhorn Gorge — Walk
• Kitakami Wilds — Walk
• Mossfell Confluence — Walk
• Oni Mountain — Walk

In Hisui (Legends: Arceus)

• Lake Verity — Walk
• Obsidian Falls — Walk
• Primeval Grotto — Walk
• Sands Reach — Walk

In Sinnoh (Diamond, Pearl & Platinum)

• Canalave City — Super Rod
• Celestic Town — Super Rod
• Eterna City — Super Rod
• Fuego Ironworks — Super Rod
• Great Marsh — Good Rod, Super Rod
• Iron Island — Super Rod
• Lake Acuity — Super Rod
• Lake Valor — Super Rod
• Lake Verity — Super Rod
• Mt. Coronet — Super Rod
• Oreburgh Gate — Super Rod
• Pastoria City — Super Rod
• Pokémon League — Super Rod
• Ravaged Path — Super Rod
• Resort Area — Super Rod
• Route 203 — Super Rod
• Route 204 — Super Rod
• Route 205 — Super Rod
• Route 208 — Super Rod
• Route 209 — Super Rod
• Route 210 — Super Rod
• Route 212 — Super Rod
• Route 213 — Super Rod
• Route 214 — Super Rod
• Route 218 — Super Rod
• Route 219 — Super Rod
• Route 221 — Super Rod
• Route 222 — Super Rod
• Route 224 — Super Rod
• Route 225 — Super Rod
• Route 227 — Super Rod
• Route 228 — Super Rod
• Route 229 — Super Rod
• Sea Route 220 — Super Rod
• Sea Route 223 — Super Rod
• Sea Route 226 — Super Rod
• Sea Route 230 — Super Rod
• Sendoff Spring — Super Rod
• Sunyshore City — Super Rod
• Twinleaf Town — Super Rod
• Valley Windworks — Super Rod
• Victory Road — Super Rod

In Johto & Kanto (HeartGold & SoulSilver)

• Cerulean Cave — Super Rod
• Fuchsia City — Good Rod, Super Rod
• Johto Safari Zone — Super Rod
• Lake of Rage — Good Rod, Static Encounter, Super Rod, Surf
• Mt. Silver — Good Rod, Super Rod
• Mt. Silver Cave — Super Rod
• Seafoam Islands — Super Rod

In Hoenn (Ruby, Sapphire & Emerald)

• Sootopolis City — Super Rod

In Kanto (FireRed & LeafGreen)

• Cerulean Cave — Super Rod
• Cerulean City — Super Rod
• Cinnabar Island — Super Rod
• Fuchsia City — Super Rod
• Pallet Town — Super Rod
• Route 10 — Super Rod
• Route 11 — Super Rod
• Route 12 — Super Rod
• Route 13 — Super Rod
• Route 22 — Super Rod
• Route 23 — Super Rod
• Route 24 — Super Rod
• Route 25 — Super Rod
• Route 4 — Super Rod
• Route 6 — Super Rod
• S.S. Anne — Super Rod
• Sea Route 19 — Super Rod
• Sea Route 20 — Super Rod
• Sea Route 21 — Super Rod
• Seafoam Islands — Super Rod
• Vermilion City — Super Rod
• Viridian City — Super Rod

In Sevii Islands (FireRed & LeafGreen)

• Berry Forest — Super Rod
• Bond Bridge — Super Rod
• Cape Brink — Super Rod
• Five Island — Super Rod
• Five Isle Meadow — Super Rod
• Four Island — Super Rod
• Green Path — Super Rod
• Icefall Cave — Super Rod
• Kindle Road — Super Rod
• Memorial Pillar — Super Rod
• One Island — Super Rod
• Outcast Island — Super Rod
• Resort Gorgeous — Super Rod
• Ruin Valley — Super Rod
• Tanoby Ruins — Super Rod
• Trainer Tower — Super Rod
• Treasure Beach — Super Rod
• Water Labyrinth — Super Rod
• Water Path — Super Rod

In Johto & Kanto (Gold, Silver & Crystal)

• Fuchsia City — Good Rod, Super Rod
• Lake of Rage — Good Rod, Static Encounter, Super Rod, Surf

In Kanto (Red, Blue & Yellow)

• Fuchsia City — Super Rod

Other games (9)

• Brilliant Diamond / Shining Pearl (Gen 8): Canalave City, Celestic Town, Eterna City, Fuego Ironworks, Great Marsh, Iron Island, Lake Acuity, Lake Valor, Lake Verity, Mt. Coronet, Oreburgh Gate, Pastoria City, Ravaged Path, Resort Area, Sendoff Spring, Pokémon League, Route 203, Route 204, Route 205, Route 208, Route 209, Route 210, Route 212, Route 213, Route 214, Route 218, Route 219, Route 221, Route 222, Route 224, Route 225, Route 227, Route 228, Route 229, Sea Route 220, Sea Route 223, Sea Route 226, Sea Route 230, Victory Road, Sunyshore City, Twinleaf Town, Valley Windworks
• Sword / Shield — The Isle of Armor (Gen 8): Ballimere Lake, Challenge Beach, Frigid Sea, Giant's Bed, Giant's Foot, Honeycalm Island, Honeycalm Sea, Insular Sea, Loop Lagoon, Snowslide Slope, Stepping-Stone Sea, Workout Sea
• Sword / Shield (Gen 8): Axew's Eye, Bridge Field, Dusty Bowl, East Lake Axewell, Galar Route 2, Giant's Cap, Giant's Mirror, Giant's Seat, Lake of Outrage, North Lake Miloch, South Lake Miloch, West Lake Axewell
• Let's Go, Pikachu! / Let's Go, Eevee! (Gen 7): Kanto Sea Route 20
• Ultra Sun / Ultra Moon (Gen 7): Akala Outskirts, Alola Route 13, Alola Route 14, Alola Route 15, Alola Route 7, Alola Route 8, Alola Route 9, Ancient Poni Path, Brooklet Hill, Hauoli City, Kalae Bay, Malie Garden, Melemele Sea, Paniola Town, Poni Breaker Coast, Poni Gauntlet, Poni Meadow, Seafolk Village, Seaward Cave, Tapu Village, Vast Poni Canyon
• Sun / Moon (Gen 7): Akala Outskirts, Alola Route 13, Alola Route 14, Alola Route 15, Alola Route 7, Alola Route 8, Alola Route 9, Brooklet Hill, Kalae Bay, Malie Garden, Melemele Sea, Paniola Town, Poni Breaker Coast, Poni Gauntlet, Poni Meadow, Poni Wilds, Seafolk Village, Seaward Cave, Secluded Shore, Tapu Village, Ula'ula Beach, Vast Poni Canyon
• Omega Ruby / Alpha Sapphire (Gen 6): Sootopolis City
• X / Y (Gen 6): Friend Safari, Kalos Route 22, Kalos Route 3, Parfum Palace
• Black 2 / White 2 (Gen 5): Nature Sanctuary

Gyarados — full Pokédex entry