The eon duo also aid Emerald during the events of the Omega Ruby & Alpha Sapphire arc, where the two Pokémon also assist Ruby and Sapphire as they must battle against Primal Groudon and Primal ...

However, your odds of finding one are fairly slim, and you won't know if Groudon is Shiny or not until you defeat the Pokemon and make it to the catching phase of the encounter. Your best bet to ...