Shiny Pokémon, Pokémon GO Wiki

Shiny Pokémon are extremely rare Pokémon that differ in coloration from their regular appearance. These color variations may range from minor hue adjustments to completely altered palettes. Only one shiny variation exists for each Pokémon. In the Map View and Sightings view, Shiny Pokémon are shown in their regular coloration until they appear on the encounter screen or on the summary page, where they have an aura of stars around them, a shiny tab shown above the CP and their different coloratio

Pokémon GO shiny Pokémon

Lillipup, Pokémon GO Wiki

New Event Pokemon Infographic : r/TheSilphRoad