Galladite

If held by a Gallade, allows it to Mega Evolve into Mega Gallade if its Trainer has a Key Stone. Each Trainer can only Mega Evolve one Pokémon per battle.

Unaffected by item negating effects (such as Embargo and Klutz). Item manipulating effects (such as Trick and Fling) cannot give Gallade a Galladite or remove a Galladite from Gallade.

If held by a Gallade, allows it to Mega Evolve into Mega Gallade when it performs a Spectacular Talent during a Pokémon Contest Spectacular while its Trainer has a Key Stone. Gallade will remain a Mega Gallade until the Talent Round ends.

Pokémon holding Galladite in Pokémon Omega Ruby and Alpha Sapphire cannot be traded to Pokémon X and Y.

In Pokémon Shuffle, the Galladite allows the player to Mega Evolve Gallade.

The player can obtain the Galladite by defeating Mega Gallade in Stage 580 found on Prasino Woods.

The Galladite enables the following Mega Evolution:

Stone	Pokémon			Type	Effect	Gauge	Max
			Mega Gallade	Fighting	Erases a jagged line of Pokémon vertically. Actually erases two jagged lines of Pokémon vertically. These lines cannot cross.	16	10

In Omega Alpha Adventure 20, the Meteor Village elder offered Sapphire a Gardevoirite and Galladite, commenting on how her Gallade and Ruby's Gardevoir are a match. Ruby and Sapphire later used these Mega Stones to Mega Evolve Rara and Kirly during a brief battle against each other.