Instructions
Masuda Method
Place a female Nidoran and a male Pokemon that is compatible with Nidoran, breeding-wise, in your party. Make sure one of the two Pokemon is from another country. You can receive foreign Pokemon by trading online through the global trade station.
Go to the daycare center and drop off both Pokemon.
Ride your bicycle around the daycare center until its owner calls you back. He will hand you an egg.
Walk around until the egg hatches. If you are lucky, the Nidoran will be Shiny.
Encountering a Shiny
Travel to either Route 35 or Route 36.
Walk around until you encounter a Shiny Nidoran.
Use a Pokeball to capture it. If the Nidoran is not Shiny, run away and try again. Remember, you have a very small chance of encountering a Shiny Nidoran.