If you want the full benefit of this tip, use a Pokemon that can evolve. Otherwise, there will be some confusion with names and so forth. First, place a flying Pokemon that has been taught FLY as the first Pokemon in your lineup, the "RED Gyarados" as the sixth position, and the Pokemon whose color is to be changed in the second position. After doing this, put all of the Pokemon back into the PC except the first one. Next, take out the Pokemon that was in the second position before, the one that will be changed. Enter the bug-catching contest that is near Goldenrod city. This is held on Tuesdays, Thursdays, and Saturdays. As soon as you enter it, exit right away. When the clerk asks you if you want to quit, make sure you say NO, which is always the lower answer. Now use your Flying Pokemon to FLY out of the contest. Store the Pokemon that will be changed in a PC, then go back to the contest and say YES, the top answer, to complete the contest. Return to a PC, withdraw the Pokemon, and check its status screen. The Pokemon will be a different color, but it will have Gyarados's name. Grow the Pokemon until it evolves. You may want to use Rare Candies if you have any. Now when you go into battle with the evolved form of the original Pokemon, it will have a shining status.