I thought about it countless times and I think I will use the Red Gyarados since I didn't use it in Gold or Silver. It makes it easier for me to obtain a Shiny and if I don't have a Water type by then, which I probably will by that point. The only thing about Gyarados, shiny or not, is his ability. It gets annoying after a while, so I may not use him for an in-game team.