Type: Steel/Psychic
Classification: Iron Leg Pokémon
Height: 8'02"
Weight: 2,078.7lbs
Ability: Tough Claws
Upon Mega Evolving, Mega Metagross gets a considerable boost to its Attack, Defense, Sp. Atk, and Sp. Def stats. In addition to a very well-rounded offense/defense stat boost, its Speed stat is also increased greatly, making it one of the best all-rounders in battle. Metagross's Ability also changes to Tough Claws, which increases the power of attacks that make physical contact.
Reference and images: Serebii.net
Additional references, images, and information: pokemonrubysapphire.com
I really want one. I beat all 8 gyms. but I have not beat the pokemon leage.