Instructions
Travel to Canalave City, which lies west of Route 218 in the Sinnoh Region. Sunyshore City, Pokemon League and Valley Windworks also house the Pokemon Gyarados. While traveling, head south on Route 223 to reach Sunyshore City, or travel north on Victory Road to reach the Pokemon League. Head east on Route 205 to reach Valley Windworks.
Go to Eterna City or Pastoria City, where odds of finding Gyarados increase from 60 percent to 65 percent of all encounters. Eterna City lies south of the Eterna Galactic Building, and Pastoria City rests south of the Great Marsh. Move toward the water in Canalave City, Sunyshore City, Pokemon League, Valley Windworks, Eterna City or Pastoria City.
Equip the Super Rod during the day to fish or use any fishing rod during the morning or night. When Gyarados appears in a random encounter, examine its color scheme. Gyarados typically bears yellow scales on its stomach, aquatic blue scales on its head and back and white fins protruding from its back. A different color scheme indicates a shiny Pokemon.
Leave the battle or knock out Gyarados if it possesses the typical color scheme. Continue entering battles until you find a Gyarados with a red color scheme, rather than a blue one. One Pokemon in 8,192 Pokemon encounters will appear shiny.
Attack shiny Gyarados until it weakens. Throw a Pokeball to capture it. Take shiny Gyarados to a Pokemon Center for healing before using it in battle.