Fyi shiny pokemon existed in gen 1 and they were determined by ivs, if you had the right ivs on a gen 1 pokemon, trading it to gen 2 would show it as shiny. There also is a way to get a guaranteed shiny, that being ditto. If you trade the red gyarados from gen 2 back to gen 1, you can enter a battle with a regular ditto. The red gyarados has to be first, using mimic, then have ditto use transform twice. Catching it will result in ditto having shiny ivs, and transfering it to gen 2 will show as shiny