Multiple users over on the Pokemon-themed Subreddit The Silph Road have posted screenshots and videos of both shiny Magikarp and shiny Gyarados.
Neither Pokemon Go developer Niantic nor publisher The Pokemon Company have mentioned that shiny versions of their popular critters would be coming to the game soon, despite both a recent patch and new Water-type event. However, since the only shiny Pokemon sighted so far have been this Water-type pairing, it may be that these rare versions are tied into that event. It remains to be seen whether yellow Magikarp and red Gyarados will be available once the events ends on March 29, and also whether more shiny critters will become available.
Shiny Pokemon were first introduced in Pokemon Gold and Silver. Red Gyarados played a major part in those games, and it's catchable for every player at the Lake of Rage. Most shiny Pokemon are extremely rare in the mainline series, however: the probability of a random creature being shiny is around 1 in 8000.
In Pokemon Go, it's apparently not made clear on the game's overworld whether a Pokemon is shiny--you'll only discover its color once you enter battle. Be warned, however: one user reported sighting a shiny Magikarp, only for it to be revealed as a regular pink Ditto. Heartbreaking.
In addition to shiny variants, fans have been requesting legendary Pokemon to be introduced for some time now. Niantic has responded by saying legendaries will be available to catch by the end of the year, though how rare they'll be remains to be seen.
Niantic has continued to support Pokemon Go since its launch in July last year. It brought creatures from Pokemon Gold and Silver to the mobile game in February, while trading will arrive at some point this year and PvP battles are also in the works.
Source: https://www.gamespot.com/articles/pokemon-go-finally-lets-you-catch-shiny-pokemon/1100-6448915/
