Although there's not much information about the upcoming Pokémon Legends: Z-A outside its initial reveal trailer, the recent appearance of a Shiny Zygarde ... Later on, in Sword and Shield ...

When you receive Zygarde in Pokemon GO, it will be in its 10% Forme ... As you track your progress along the route, you will find a shiny object on the ground. This object is a Zygarde Cell ...