On Route 10, which is also known as the Menhir Trail, Xerosic stands among the mysterious array of stone lines with Bryony as a female Flare Grunt reports to him that Mable of team B has confirmed the normal functionality of the machinery beneath the stones. Xerosic giggles that luck is on their side, and states that their scheme was basically shattered when Xerneas destroyed the Absorber on its way out of their HQ. However, it would appear that stone lines created by AZ 3000 years ago were in fact the ancient Absorber he used. He asks Bryony if she managed to gather any information, and Bryony replies that residents of Geosenge have said that a scientist with weird hair-do once mentioned about the stones emitting a mysterious energy, which supports the theory that the stones were part of the ancient Absorber. The piece of information delights Xerosic, and he believes that with the bulk of Pokemon they have acquired to harness bioenergy from, they will surely succeed in getting the Ultimate Weapon to purify the land this time.

That said, something actually still concerns Xerosic, something said by AZ when he escaped from their grasp earlier during the whole Geosenge drama. At that time, Malva arrived with Yveltal, and quickly began to clash with Xerneas. Down at their HQ's basement, Xerosic discovered with astonishment that AZ has managed to break free, and before the giant man departed, he stated that Team Flare's scheme would never be fulfilled because they were interfering with the balance. AZ mentioned that 3000 years ago, when the ecosystem of Kalos was disrupted, the Watcher who kept the order appeared, and with Xerneas, Yveltal and the Ultimate Weapon all in play, they have easily exceeded the conditions to get this creature's attention, who shall put them under surveillance. With a grin, AZ enigmatically stated that Z the Watcher would foil their plan, and vanished in a flash of light before Xerosic could stop him.

Despite his extensive knowledge in many things, Xerosic only managed to find out that Z the Watcher refers to the order Pokemon, Zygarde. He has absolutely no idea what kind of Pokemon it is, and feels uneasy that it seems to have to ability to watch upon their actions at all times. The fact is, he has sent off Essentia to hunt it down, but isn't sure what would turn up. Moving back to the computer station, he steals a glance at the monitor screen that keeps track of Essentia's status and sees that she is on her way to Anistar City's Pokemon Center. However, he soon notices that something is wrong, and bolts with alarm that her head gear has been damaged. He wonders what could have happened, and quickly tries to get in touch with the masked trainer.

Meanwhile, at Anistar City, Essentia activates her Pokeball Jack ability, and draws out Xerneas from its Pokeball under her command. Tierno, Trevor and Shauna gasp in shock, but the most astonished of all is Sycamore, who is seeing the legendary blue deer for the first time with his very own eyes.

Y feels frustrated that her excitement of being finally able to use Mega Evolution is overshadowed by the fact that Xerxer is her first opponent, and X suggests she leave it to him so as not to feel torn about it. However, after a moment of thought, Y believes that she is capable of handling it, and orders a Night Slash from Solsol. The Mega Absol immediately lunges forward to strike at Xerneas, but the giant deer is barely fazed and kicks into its opponent with its forelegs, sending Solsol and Y crashing into the wall. X cries out in horror, but Y assures him that she is alright. In fact, she could sense that Xerxer has held back during its kick, which means it has not been fully controlled by the enemy. Indeed, Essentia notices as well that she couldn't exert full command over Xerneas with the Pokeball Jack virus, signifying that it doesn't work easily on legendary Pokemon.

X states that instead of attacking Xerxer, they should focus on Essentia, who is standing on the deer's forehead. He tries to hit aerially with Rute, who has gained the Flying type after Mega Evolution. However, just the Mega Pinsir is about to land a strike, Essentia orders a Gravity from Xerneas to bring it down, slamming X against hard against the ground as well. Tierno, Trevor, and Shauna cringe at the scene, and Y comes up with a plan. She gets X to have Rute latch onto Solsol's tail with its horns, and begins charging forward with an Iron Tail. As the move connects with Xerneas's forehead, Rute and X is propelled towards Essentia, who tries to stop them with Xerneas's Aurora Beam. However, X quickly orders a Feint from Rute, which strikes with priority and manages to chip off a part from Essentia's head gear.

Stunned from the attack, Essentia fights to stay balanced on Xerneas's head, and suddenly notices the approach of a gigantic serpentine creature from the next alley, who is no other than Zygarde, the Kalos Watcher. She is surprised that Z is still nearby, and everyone else is soon alerted to its presence. Trevor turns to Sycamore to inquire about its identity, but the professor himself reveals that he has never seen such a Pokemon before as well. Y wonders if it is yet another new foe, and gets Solsol ready to fight. However, she soon hears Xerxer speaking to her telepathically, who is telling her to stop. Y is surprised that Xerxer has broken free from Essentia's Pokeball Jack effect, but Xerneas states that it is still under her control. Yet, X's attack earlier managed to damage part of the controlling device, which allowed it to speak to her with telepathy. It explains that the green serpentine Pokemon is Zygarde, the Watcher, who is neither a friend nor a foe. It has simply come to suppress its powers.

Essentia feels frustrated that not only has she failed to fully control Xerneas, but Z has also come at such a time to intervene. She sends out Trevenant, and commands it to restrain Zygarde with its tree roots. At that moment, Green arrives in Anistar with Diantha on his Charizard, and is bewildered by the scene in front of his eyes. In the next instant, the hexagonal patterns on Zygarde's body start flash in a intense white light, and green squishy blobs start to materialize everywhere, from the trees, the soil, and even the very ground that the Vaniville kids are standing on. Soon, the green blobs detach from the surfaces they form on, and rapidly fly towards Zygarde's body like a swarm of insects. Shauna gasps that the Pokemon is absorbing all the green squishy material, and Essentia knows that it must be gathering forces from nature, which also means that it is currently in a defenseless state most vulnerable to capture. Without further hesitation, Essentia hops towards Zygarde, and slams a Pokeball onto its head. In a blinding flash of light, the Kalos Watcher vanishes from sight and the masked trainer lands on the ground, panting to catch her breath.

Back on Xerosic's side, things are getting hectic as the Grunts discover that the remote control system of Essentia has failed to work as well. A male Grunt reports that he has dispatched spies at Anistar to gather information, but Xerosic barks that what they are dealing with is of extreme urgency. He states that the Expansion Suit is reaching its activity limit, and normally its artificial intelligence should activate its defense system and automatically initiate a retreat command. However, this is not happening for some odd reason, and he starts to wonder if it is possible that the test subject herself is somehow intervening. At that moment, the monitor screen displays the alert that all connection has been cut off from Essentia, which causes the red-haired Scientist to grunt with angst and frustration.

On the streets of Anistar City, something seems to be going on with Essentia as she crouches motionlessly on the ground while panting for air. However, before X could reach her, she suddenly leaps into the air and flies off into the distance. Y wonders where Zygarde has gone, and Green, who has landed his Charizard with Diantha, realizes that the serpentine creature is the legendary Pokemon he was searching for. Diantha reveals that while in midair, they saw Essentia capture Zygarde, and Trevor is surprised that Green and Diantha seem to know about the Pokemon. Diantha explains that Zygarde was the reason Green came to Kalos, as it is their key to victory in their battle against Team Flare. Shauna is alarmed that their key to victory is now in the hands of Team Flare, but Tierno thinks they should at least be grateful that they managed to get Xerxer back. Y grins that it was all thanks to X, but the boy apparently has something else on his mind. He states that after Rute made a crack on Essentia's helmet, he could faintly see the face of the person inside. However, during their battle, he became aware that her eyes were always shut, which implies that the person inside Essentia is constantly in a slumber state.

X's revelation causes everyone to gasp in bewilderment, but their attention is soon drawn to Sycamore, who suddenly lets out a cry of shock. Trevor wants to know what is wrong, and realizes that the professor is using the Holo Caster to communicate with his assistants Sina and Dexio, who are currently at the Lysandre Café. It turns out that during their investigation, the two have engaged in a battle against the Garçon, who was unsurprisingly a Team Flare Grunt. After subduing the Grunt, Sina and Dexio have successfully forced him to talk, and learnt that Lysandre and Malva are currently at a place known as the Pokemon Village…