"Mega" Evolution

Recent developments in the study of Pokémon metamorphosis, commonly referred to as "evolution" have resulted in several Pokémon being able to temporarily advanced beyond their natural limits of physical transformation.  This new variety of metamorphosis is called Massive Evolutionary Grade Advancement, commonly referred to as "Mega Evolution" but is really just another stage of metamorphosis.  It is speculated that these temporary transformations might someday occur naturally, and become permanent, but for now this is not the case.

The effect is achieved by rapidly increasing a Pokémon's Ersatz Vitamine to the point where the Pokémon's body is not physically capable of handling the effects.  Special items known as "Mega Stones" are used for this, although it is theoretically possible for it to happen naturally.  As a defense mechanism, the Pokémon will undergo "Mega Evolution," creating a new body that is capable of handling the immense and sudden increase in power.  Once the Ersatz Vitamine levels decrease to normal, the Pokémon's new body no longer possess the required amounts of energy to sustain itself, so the Pokémon will return to its normal form.

The following is a list of Pokémon currently known to possess a Massive Evolutionary Grade Advancement:

Venusaur
Charizard (X and Y)
Blastoise
Alakazam
Gengar
Kangaskhan
Pinsir
Gyarados
Aerodactyl
Mewtwo (X and Y)
Ampharos
Scizor
Heracross
Houndoom
Tyranitar
Blaziken
Sceptile
Swampert
Gardvoir
Mawile
Aggron
Medicham
Manectric
Banette
Absol
Latias
Latios
Garchomp
Lucario
Abomasnow
Slowbro
Sableye
Altaria
Salamence
Metagross
Lopunny
Audino
Diancie
Gallade
Sharpedo
Camerupt
Rayquaza
Beedrill
Pidgeot
Glalie
Steelix