How to get Greninja Mega Stone in Pokémon Legends Z-A

If you're looking to Mega Evolve Greninja using the Greninjite Mega Stone, you will need to participate in Ranked Battles.
Game Rant on MSN

Mega Greninja's Days Are Numbered in Pokemon Legends: Z-A

Z-A introduced a fan-favorite new Mega Evolution in the form of Mega Greninja, but there is bad news for its fans.