Mega Evolutions are Pokemon that evolve once again using a Mega Stone. There are specific stones for each Mega Pokemon, for example, Blaziken can only evolve with a Blazikenite. You have the choice to evolve them in battle if they are holding their Mega Stone. Once the battle is over, they return to their original form and you will have the chance to evolve them again next battle.
US Name: Mega Venusaur
Jp. Name: Mega Fushigibana
Type: Grass/Poison
Classification: Seed Pokémon
Height: 7' 10"
Weight: 342.8 lbs.
Ability: Thick Fat
First Appearance: Pokémon X & Y
Details:
This Pokémon was first revealed in the Pokémon Direct on September 4th. This Pokémon is to Mega Evolve from the Bulbasaur you receive from Professor Sycamore in Lumiose City. It has increased Defense and Special Defense stats.


US Name: Mega Charizard
Jp. Name: Mega Lizardon
Type: Fire/Flying
Classification: Flame Pokémon
Height: 5' 07"
Weight: 221.6 lbs.
Ability: Drought
First Appearance: Pokémon X & Y
Details:
This Pokémon was first revealed in the Pokémon Direct on September 4th. This Pokémon is to Mega Evolve from the Charmander you receive from Professor Sycamore in Lumiose City. It has a significantly increased Special Attack stat

US Name: Mega Blastoise
Jp. Name: Mega Kamex
Type: Water
Classification: Shellfish Pokémon
Height: 5' 03"
Weight: 222.9 lbs.
Ability: Mega Launcher
First Appearance: Pokémon X & Y
Details:
This Pokémon was first revealed in the Pokémon Direct on September 4th. This Pokémon is to Mega Evolve from the Squirtle you receive from Professor Sycamore in Lumiose City
MEGA EVOLUTIONS







US Name: Mega Kangaskhan
Jp. Name: MegaGarura
Type: ??
Classification: Parent Pokémon
Height: ??
Weight: ??
Ability: Parental Bond
First Appearance: Pokémon X & Y
Details:
This Mega Evolution was first shown in the Video Game Championships in Vancouver in August 2013. It's unique in that is allows the baby in Kangaskhan's belly to come up and battle with the focal point of the evolution being based on the baby
​
US Name: Mega Ampharos
Jp. Name: MegaDenryuu
Type: Electric/Dragon
Classification: Light Pokémon
Height: 1.4m
Weight: 61.5kg
Ability: Mold Breaker
First Appearance: Pokémon X & Y
Details:
This Mega Evolution was first shown in August 2013's issue of CoroCoro. It features the special ability of Mold Breaker and features a change in type to Electric/Dragon
US Name: Mega Absol
Jp. Name: MegaAbsol
Type: Dark
Classification: Disaster Pokémon
Height: 1.2m
Weight: 49.0kg
Ability: Magic Bounce
First Appearance: Pokémon X & Y
Details:
This Mega Evolution was first shown in August 2013's issue of CoroCoro. It features the special ability of Magic Bounce. It has an increase Attack and Speed
US Name: Mega Mawile
Jp. Name: MegaKucheat
Type: Steel/Fairy
Classification: Deceiver Pokémon
Height: 1.0m
Weight: 23.5kg
Ability: Huge Power
First Appearance: Pokémon X & Y
Details:
This Mega Evolution was first shown in August 2013's issue of CoroCoro. It features the special ability of Huge Power. It has increased Defense & Special Defense
US Name: Mega Lucario
Jp. Name: MegaLucario
Type: Fighting/Steel
Classification: Aura Pokémon
Height: 1.3m
Weight: 57.5kg
Ability: Adaptability
First Appearance: Pokémon X & Y
Details:
This Mega Evolution was first shown in August 2013's issue of CoroCoro. It features the special ability of Adaptability. It also has an increase Attack stat
US Name: Mega Blaziken
Jp. Name: MegaBashamo
Type: Fire/Fighting
Classification: Blaze Pokémon
Height: 1.9m
Weight: 52.0kg
Ability: Speed Boost
First Appearance: Pokémon X & Y
Details:
This Mega Evolution was first shown in August 2013's issue of CoroCoro. It features the special ability of Speed Boost and has an increased Attack stat
US Name: Mega Mewtwo Y
Jp. Name: Mega Mewtwo Y
Type: Psychic
Classification: Genetic Pokémon
Height: 1.5m
Weight: 33.0kg
Ability: Insomnia
First Appearance: Extremespeed Genesect: Mewtwo Awakens
Details:
This Pokémon was first leaked in a promotional pamphlet of the Present Guide for the movie Extremespeed Genesect: Mewtwo Awakens, replacing Mewtwo on the poster with a caption calling it the Eclair Forme. However, soon afterwards it was revealed by Pokémon Smash, though without saying it is actually a Mewtwo form with the official sites stating it as a new Pokémon.
It was eventually confirmed as a Mega Evolution in CoroCoro in August 2013 and was revealed to be exclusive to Pokémon Y in September 2013

US Name: Mega Mewtwo X
Jp. Name: Mega Mewtwo X
Type: Psychic/Fighting
Classification: Genetic Pokémon
Height: 2.3m
Weight: 127.0kg
Ability: Steadfast
First Appearance: Pokémon X & Y
Details:
This Pokémon was revealed within the October issue of CoroCoro in September 2013. It is a Mewtwo Evolution that is exclusive to Pokémon X and has a different type to its counterpart in Pokémon Y

US Name: Mega Garchomp
Jp. Name: Mega Gaburaisu
Type: Dragon/Ground
Classification: Mach Pokémon
Height: 1.9m
Weight: 95.0kg
Ability: Sand Force
First Appearance: Pokémon X & Y
Details:
This Pokémon was revealed within the October issue of CoroCoro in September 2013.