Mega Evolution

Mega Pokémon are a new evolution method of Pokémon introduced in earlier generations. Some Pokémon need special Mega Stones in order to evolve into their Mega forms, the final forms for one-evolution families and second/true final forms for two-evolution families. Also; Pokémon can only enter their Mega Evolution Form by using the Mega Stone unique to their Species. For example: To Evolve Blaziken into Mega Blaziken; Blaziken must be holding the Mega Stone Blazikenite.

Mega Evolution does more than just change a Pokémon's appearance, it can also change their Type, Ability and Stats. A good example is Ampharos; which after Mega Evolution becomes a Dual Type Electric/Dragon Pokémon.

Mega Evolution is only possible during a Battle, however you can also attack in the same turn. After the Battle ends, the Pokémon devolves back into previous form but they still evolve. You are limited to having only one Mega Evolution in a battle. All your team can however hold Mega Stones. Each individual Mega Stone can be used an infinite number of times, but only once per battle.

Trivia

 * Mew and Ditto can both take on the form of a Mega Evolution, but cannot Mega Evolve themselves.
 * Kangaskhan is the only Pokémon that does not have an appearance change when it Mega Evolves. Instead, the baby in its pouch comes out to assist in the battle.
 * Mewtwo and Charizard have two Mega Evolutions. The different evolutions are obtained with version-exclusive Mega Stones - for example Mewtwonite X can only be obtained in Pokemon X and causes Mewtwo to evolve in Mega Mewtwo X. The item can be traded between versions.
 * Blaziken is currently the only Pokémon whose Mega Evolution cannot be obtained through normal gameplay. Instead, an event will be held where player can receive a Torchic holding the Blazekinite, Blaziken's Mega Stone. Soon after that player can evolve Torchic all the way to Blaziken and let Blaziken Mega Evolve by holding the Blazekinite.
 * Blaziken is also the only non-Kanto starter to recieve a Mega Evolution so far.
 * Each Mega Evolved Pokémon has +100 stat increased than original, with the exception of Mega Mewtwo X, it's Attack stat increses by 200.
 * Mega Evolution X brings a type change in Pokémon.
 * Mega Evolution was originally the transformation method, but keep the method as evolution method.
 * Mega Evolution is a cross between Forme Change and Evolution.
 * Because of evolution method, some of them still evolves with the Mega Stones.
 * Despite being introduced in Generation VI, none of the Pokemon from Generation VI (or Generation V for that matter) have a Mega Evolution.
 * Generation I has the most Pokémon with a Mega Evolution at 10, while Generation IV has the least amount with 3.