First off, since, you can no longer hatch Magikarp from an egg, the only way to obtain a shiny one yourself is to catch one.
Pokemon GO's new event helps increase the chances of running into water-type Pokemon. Lucky for you, we've just been given a water-Pokemon event, so catching heaps of Magikarp shouldn't be too hard. Apparently, there was something else that developer Niantic left out of the update, however, as shiny Magikarp have now been spotted roaming about the world by intrepid players.
If you have any doubt about it, make sure you catch it, because then you can make sure.
How rare are shiny Pokemon in "Pokemon Go"?
"The best I can do is show the shiny and the journal entry".
Shiny Pokemon will evolve into their shiny counterparts at higher levels. And now, it's been confirmed that shiny Magikarp and shiny Gyarados have been found in Pokemon GO!
Shiny Pokedex Buttons have also been added and while many fans may not have noticed yet, alongside the new Pokedex gender buttons are new Pokemon variant buttons for Shiny Pokemon.
If you are in places where the water Pokemons usually roam free, such as next to lakes, rivers, water streams or similar, you will see an increase in the spawn rate for the Gen 2 water Pokemons in the Johto region. Users in low spawn areas that have a Pokestop nearby - now's the time to Lure.
Nobody yet knows what that number is for Pokemon Go, but there's evidence to suggest that they are about that rare. There's a 1 in 6 chance that the user gets an ideal moveset when evolving Magikarp into Gyarados. Apparently yes - have a peek at this monstrous beast. Good luck in finding one of these!
One interesting aspect of the event is that there are no bonuses or sales linked to it.