Swampertite

If held by a Swampert, allows it to Mega Evolve into Mega Swampert 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 Swampert a Swampertite or remove a Swampertite from Swampert.

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

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

In Pokémon Shuffle, the Swampertite allows the player to Mega Evolve Swampert.

The player can obtain the Swampertite by completing Mission Card 18.

The Swampertite was also available as a prize during the Mega Swampert Competitive Stage. This Competitive Stage ran on both the Nintendo 3DS and Mobile versions from January 5 to 12, 2016 and May 10 to 17, 2016. It ran on the Pokémon Shuffle Mobile from May 10 to 17, 2016.

The Swampertite enables the following Mega Evolution:

Stone	Pokémon			Type	Effect	Gauge	Max
			Mega Swampert	Water	Replaces Pokémon (max 3) of the same type as Mega Swampert. Converts three tiles containing a single Water type into Mega Swampert.	12	6

In Omega Alpha Adventure 2, it was revealed that Steven had found a Swampertite for Ruby's Mumu.