A Mega Stone is a held item which allows certain Pokémon to mega evolve. In Pokémon Reborn, they appear as grey Pokéballs on the ground which can be picked up but can also be given to the player by NPCs. ...

How do you get the mega ring in Pokémon Reborn?

Go to the Grand Hall in the Opal Ward and talk to DJ Arc and he'll tell you that it's a shame about the other trainers he wasn't able to track down and that it's up to you to take good care of the remaining Pokemon. Your Reward will be the Mega-Z Ring with it you'll be able to use Mega Stones and Z-Moves.

In which Pokémon game is mega evolution?

Mega Evolution is a mechanic in the Pokémon series, introduced in Pokémon X and Y. It is a temporary mega evolution that can be initiated in battle if the Pokémon is holding the Mega Stone for their species, however, only select Pokémon can undergo Mega Evolution.