If you mean the Red Gyrados as in the one from Gold Silver and Crystal that you were 100% guaranteed to come across through normal playing then there isn't one. The only possibility of finding a red Gyarados is just being lucky enough to come across either a shiny Magikarp, catching it and then evolving it or catching a shiny Gyarados.
red gyrados is just shiney gyrados use the shiney code and find gyrados
The red Gyrados is found in the Sendoff lake at the Spring Path.
The red qyrados is just a shiny grados and u can get gyrados when fishing with a good/super fishing rod imn Sinnoh
Two ways By Luck Action replay
it can range from where u are fishing, u can get seadra, tentacruel, tentacool, krabby, magikarp, gyrados, poliwag, poliwhirl and many other pokemon.
use pokeradar on a body of water that has lots of gyrados
Actually there is no red Gyrados. I mean there is, but a red Gyrados is a shiny Gyrados.
to get a red gyrados you have 1% of finding a red gyrados and you have to use a super rod to find a red gyrados.
red gyrados is actually a 'shiny' gyrados, meaing it's just a weird thing that the Pokemon games have were every couple 10,000 Pokemon or so. so in order to obtain a red gyrados you would have to go through quite a lot of finding a shiny gryados or shiny magikarp(if you evolve taht it should stay shiny)
The Red Gyrados drops it. If you already fought the Red Gyrados, you should already find it.
You Can't catch a red gyrados Unless it's a shiny Now you can do that by chaining or Action Replay It's your choice
Gyrados's shiny color is red to get a red gyrados is very hard it takes 8000 chances or so to see it keep finding gyrados until its red.