Your thinking of Pokemon Silver/Gold/Crystal, which has a Shiny Gyarados, which is part of the Plot, which you will have to fight at one point. Same for Soul Silver and Heart Gold, which also features a Red Gyarados.
In Diamond/Pearl/Platinum, the only way you will encounter a Red Gyarados is in the wild. The chances are 1/8192 in finding a Shiny Pokemon. If you breed a Shiny Gyarados or Magikarp, and it has an egg, the egg has a 1/69 chance of being shiny.
Easy! Just trade the red gyarados from soulsilver to diamond.
a red gyrandos is a shiny Pokemon and it lives with other gyrandos-in water
he's.... MR. POKEMON
its just a rare Pokemon also its gyarados
it is a red garados (remember shiny Pokemon are rare)
You get him at the LAKE OF RAGE north of maghony town.
You get the red shard from the red garados if you fail to catch it at the lakeof rage.
your a fag
i will trade shiny garados for ryquaza at 3:00 u.s.a my name ash fc 5198 4590 6757
use a super rod
You have to have a action replay ds so you can get weird colored pokemon.
You can trade it from heart gold/ soul silver or get lucky and find a shiny magicarp (golden/yellow) and evolve it into shiny gyarados (red gyarados)