Pokemon GO developers released Shiny Necrozma as part of the GO Fest 2024: New York City event. You can get Shiny Necrozma by winning Necrozma 5-Star Raids, Dusk Mane Necrozma raids, and Dawn Wings Necrozma raids as a reward encounter. While there is a chance to encounter a Shiny Necrozma, getting a legendary Shiny Pokemon is extremely challenging.