The official Japanese Pokémon website has revealed details on the upcoming TV special "The Strongest Mega Evolution ~Act IV~".

The Strongest Mega Evolution ~Act IV~ will air this fall! What is this green, Pokémon-like thing that appeared in the trailer for next year's Pokémon movie!?

A special episode of the currently airing, popular anime "Pocket Monsters XY", titled "The Strongest Mega Evolution ~Act IV~", will air this fall! Incredibly, the green Pokémon-like thing that appeared in the trailer for next year's Pokémon movie has also been confirmed to appear! What kind of role will it play in the story? Play close attention to the upcoming information!

Story

Alan's journey in pursuit of becoming the strongest once again takes him to the Kalos region. Wanting to become even stronger, he bets his Mega Ring and Mega Stone on being able to defeat 10 Mega Evolution users in a row.
Alan throws himself into battle. Manon is worried sick about Alan. And Manon's partner, Hari-san the Harimaron, meets a mysterious being. It all leads up to something seriously major...
We've finally reached the final act of the story! Don't miss the shocking climax!!

Characters

"Alan"
A Trainer who travels around to "master Mega Evolution and stand on the top as the strongest".
Although he studied Mega Evolution with Professor Platane once, he...
His partner Lizardon can mega evolve into Mega Lizardon X.

"Manon"
A new Trainer just starting her journey.
She refers to her partner Harimaron as "Hari-san", and always asks it for help.
She travels together with Alan out of a desire to to one day mega evolve herself.

"Daigo"
The Champion of the Houen Region.
He spends his time researching the roots of Mega Evolution.
His partner is an alternate-colored Metagross,
and he has an amazing battle with Alan, using his mega evolved Mega Metagross against Alan's Mega Lizardon X.

"Fleur-de-lis"
A celebrity in the Kalos Region working for Fleur-de-lis Labs.
He gave Alan his Mega Ring and Mega Stone and told him to become stronger if he wanted to protect the people important to him.
It appears he's conducting research on Mega Evolution energy and the Kalos Region's legends, but......?

"Pachira"
A member of the Kalos Region's Elite Four, her partner is a Hellgar.
She and her mega evolved Mega Hellgar stand blocking Alan and Mega Lizardon X's way.
She has the appearance of a news anchor, but is also apparently on friendly terms with Fleur-de-lis!

Voice Cast

Alan: Kensho Ono
Manon: Mikako Komatsu
Daigo: Kenichi Suzumura
Platane: Hiroshi Tsuchida

Staff

Executive Director: Kunihiko Yuyama
Director: Tetsuo Yajima
Series Construction: Atsuhiro Tomioka
Character Design: Toshihito Hirooka
Executive Animation Director: Toshihito Hirooka
Art Director: Katsuyoshi Kanemura
Color Keys: Noriyuki Yoshino
Director of Photography: Tairin Suzuki
Editor: Toshio Henmi
Music: Shinji Miyazaki
Sound Recording Director: Masafumi Mima

This story is centered around a young Trainer named Alan and his partner Lizardon.
"To master Mega Evolution, to defeat all mega evolved Pokémon and stand on top as the strongest":
That is the goal of Alan's journey.

In order to accomplish this, they engage in Mega Evolution Battles against powerful opponents.
They even battle Zumi of the Kalos Region's Elite Four's Mega Kamex....

Also, on their journey they encounter the newbie Trainer Manon and end up traveling together with her.

Trailer

Source: http://www.pokemon.co.jp/info/2014/09/140919_a01.html?i001=news