If held by a Steelix, allows it to Mega Evolve into Mega Steelix 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 Steelix a Steelixite or remove a Steelixite from Steelix.
Outside of battle
If held by a Steelix, allows it to Mega Evolve into Mega Steelix when it performs a Spectacular Talent during a Pokémon Contest Spectacular while its Trainer has a Key Stone. Steelix will remain a Mega Steelix until the Talent Round ends.
The player can obtain the Steelixite by completing the competitive stage available in Week 5 of the event rotation.
The Steelixite was also available as a prize during the Mega Steelix competitive stage. This competitive stage ran on the Nintendo 3DS version from December 1 to 8, 2015; August 2 to 9, 2016 and September 26 to October 3, 2017. It ran on the Pokémon Shuffle Mobile from August 2 to 9, 2016; and September 26 to October 3, 2017.
The Steelixite enables the following Mega Evolution:
A Steelixite worn by Brock's Steelix appeared in When Regions Collide!, where Brock used it to Mega Evolve Steelix during his battle with Kiawe. The Steelixite didn't appear equipped on Steelix, but rather, it appeared on its head right before Mega Evolving.
