mega rayquaza

The Mega-Evolved form of Rayquaza.

Uniquely, Rayquaza possesses what is called a mikado organ, which stores the energy from meteoroids it consumes and acts akin to a biological Key Stone. When Rayquaza then connects with the fervent wishes of humans, it will Mega Evolve.

To date, Mega Rayquaza features the highest base-stat total among all usable Pokémon, at 780, and is the sole Mega-Evolved Pokémon capable of freely holding any item, as it requires no Key Stone to Mega Evolve.

This tag implicates rayquaza (learn more).