The easiest method is to catch a Shiny Gible and evolve it into Shiny Garchomp. Alternatively, players can trade for a Shiny Garchomp or the other monsters in its evolutionary line with friends.

Capture Shiny Gible for evolution or trade with friends. Utilize Mega Energy for Shiny Mega Evolutions. Mega Garchomp and its Shiny (right) in Pokemon GO (Image via The Pokemon Company ...