Forming a More Perfect Union! (Japanese: 反撃のジガルデ！カロス最終決戦！！The Zygarde Counterattack! The Final Decisive Battle of Kalos!!) is the 136th episode of Pokémon the Series: XY, and the 935th episode of the Pokémon anime. It first aired in Japan on September 15, 2016 as a one-hour special alongside XY135 and in the United States on December 17, 2016.
An amazing assembly of powerful Pokémon and Trainers—including the Kalos Gym Leaders and two Champions—have come to help our heroes stop Team Flare! This teamwork allows Ash and Alain to rescue Chespie from inside the Giant Rock, and it seems to be defeated...until it rises once again, under Lysandre’s control.
Things seem hopeless until Squishy persuades the other Core to join the fight. The two of them merge together to become the titanic Zygarde Complete, which puts a stop to Lysandre’s plan once and for all.
Finally, it’s time for Squishy and Bonnie to say their goodbyes—but they’ll always remember their unwavering friendship that helped save the world!
As Alain and Ash approach the center, a vine rises up to attack them, but it is hit by Seed Bomb. Ash looks up and is surprised to see Team Rocket in a helicopter with Gourgeist having launched the attack. Jessie tells Ash to not just stand there, but a vine rises up and attacks the helicopter, sending Team Rocket flying. Gardevoir uses Psychic to save them. At a Pokémon Center, Sawyer, Trevor, Shauna, and Tierno watch the action unfold on TV as Diantha and Steven Stone assist with their Pokémon, Gardevoir and Metagross. The two Pokémon use Psychic to wrap up the attacking vines. They continue to attack the vines, but Steven and Diantha find themselves trapped as Blaziken Mask and Blaziken are attacked. Squishy and Z2 observe the battle, with Z2 expressing surprise that they are continuing to fight. Squishy tells Z2 that it knows not all humans are bad after having watched the humans on their journey. Reaching the center, Ash orders Pikachu to use Electro Ball and Greninja to use Water Shuriken as Alain orders Charizard to attack with Flamethrower. The attacks are blocked with vines, but with support and determination, they break through and enter the rock. They spot Chespie lying overhead, and Alain goes to free Chespie, only for crystals to block his path. Ash promises to cover Alain as best as they can whilst he goes to free Chespie. As another crystal goes to attack, Ash orders Pikachu to use Electro Ball and has Greninja use Cut, which cuts through the crystals. Outside, the Rock continues to move as Serena commands Braixen, Pancham, and Sylveon to attack. The vines surround them, and a vine goes to attack Mairin. As Alain nears Chespie, another crystal looms in front of him, but Ash orders Greninja to use Water Shuriken, which breaks the crystal. As more crystals appear to attempt to stop Alain, he reaches Chespie. Outside, the vines are about to hit Mairin when they stop. The rocks also stop moving. Ash and Alain, along with their Pokémon, emerge from the Rock, having freed Chespie. Everyone looks on, pleased that the crisis has been averted.
Mairin hugs Chespie, who is still unconscious, and thanks Alain for his work. Steven says all they have to do now is to destroy the Rock. As Team Rocket films the scene, all of their Pokémon launch an attack on the Rock, which knocks it down. Ash wonders if the attack worked, but the Rock recovers while Lysandre appears, vowing to still destroy the world. Lysandre has the Rock launch an attack at the group, but Valerie has Spritzee use Light Screen, which minimizes the damage. As everyone recovers from the hit, Bonnie and Clemont are surprised when Blaziken Mask's mask comes off, revealing that he is their father. Meyer has been injured, but insists he is alright as the Giant Rock begins moving forward again. Alain wonders how they can stop it, and Clemont points out the device on Lysandre's wrist. Alain realises that they have to destroy it. As everyone prepares to fight, Z2 notes that they are actually prepared to fight. Squishy informs Z2 that neither humans nor Pokémon will give up, even though Z2 feels they are too weak. Squishy says that their real strength lies in working together, caring about each other, and having the power to believe in themselves and find the will to succeed. The Rock launches another attack that sends them all flying. Seeing this, Z2 decides to believe in them as Squishy does, and they both jump down from Bonnie's arms. Bonnie moves to go after them, but Meyer stops her as the Cores confront the Rock. They call on every Cell in the world as everyone watches them become Zygarde Complete Forme. Seeing Zygarde, Olympia recognises the deep green eyes from her prophecy. Lysandre notes that they hid this Forme from him and confronts Zygarde, saying it must have seen what this world is like and wonders what could be worth defending. Zygarde states this world belongs to the others and is protecting them. The Rock launches another attack, which is countered by Dragon Pulse. The Rock sends more vines towards Zygarde, who dodges before attacking with Extreme Speed. Seeing their chance, Ash and Alain order Pikachu, Greninja, and Charizard to use Thunderbolt, Water Shuriken, and Flamethrower respectively on Lysandre. The device falls off of Lysandre's wrist. Zygarde manages to break through the Rock with Extreme Speed before attacking the Rock with Core Enforcer, destroying it. Lysandre, who refuses to accept that he has been defeated, falls into the explosion, ending the crisis once and for all. Those watching along on TV cheer.
Diantha thanks everyone for their help as Steven wonders what became of Lysandre. Malva doesn't care and heads off, telling Steven to let her clean up Team Flare before turning herself in to Officer Jenny. Chespie wakes up from its coma, which makes Mairin happy as she thanks Alain for his help. Alain is pleased that Chespie is safe and asks Mairin to forgive him. Zygarde approaches Ash and his friends as Squishy thanks Bonnie for looking out for it. Zygarde then restores order to the world, removing all the vines from Lumiose City and causing the red sky to disappear. Once the world is restored, Zygarde disassembles, leaving Squishy and Z2 floating in the air. Chespie approaches Squishy, who remembers that Chespie freed him from Lysandre Labs and expresses its gratitude. Squishy thanks Bonnie for taking it on a journey, allowing it to see that humans can be trusted to protect the world. Bonnie realises that Squishy is saying goodbye, and Squishy confirms it must leave to restore its energy. Squishy and Z2 rise into the sky, sharing a fond farewell with their friends as they both disappear into the sky. Bonnie tells Squishy how much it means to her. Just after they leave, the sun rises over Ash, Alain, and their friends, who all helped to save Kalos and the world from Team Flare.
Shortly after Ash and Alain enter the Giant Rock, Alain isn't wearing his Mega Ring.
This episode states that all of the Zygarde Cores and Cells from across the world are required in order to achieve Complete Forme. However, in Volcanion and the Mechanical Marvel, Squishy was able to assume Complete Forme without all of them, albeit temporarily.
When Lysandre first returns to take control of the Giant Rock, in the original Japanese version, he states that the countdown to the destruction of the world continues and that he will destroy the world even if it costs him his own life. In the English dub, the first portion of this line is removed completely, and the second portion is rewritten to have Lysandre say he will destroy the world even if he is stopped. As a result of this edit, Lysandre only speaks when the view zooms in on him, leaving the prior pan shot up the Giant Rock with no dialogue.