At the Team Flare Secret HQ, X makes up his mind on which Pokémon to Mega Evolve, and proceeds to retrieve Marisso and Salame. He sends out Lasma, Elec and Kanga at the same time, and his action surprises both Xerosic and Lysandre, since all three Pokémon are capable of Mega Evolution. Lysandre is slightly apprehensive however, since X has not Mega Evolved either of them, and believes that the boy is waiting for him to make the first move.

Taking the cue, the Team Flare Boss wastes no time in ordering a Hyper Voice from Pyroar, Dual Chop from Mienfoo, and Bite from Mega Gyarados. Mega Gyarados lunges forward, and chomps down hard onto Elec's torso with its sharp fangs. The Manectric cringes in pain, but retaliates with a Wild Charge on X's command, which zaps Mega Gyarados violently through its open mouth, forcing it to let go. X observes Mega Gyarados's status as it pants to recover from the electric shock, and states that Mega Evolution seems to have changed Gyarados's type from water and flying to flying and dark. On second thought, he believes that it is more likely water and dark, and Lysandre is interested to know what made X come to the conclusion. X points out that Gyarados's Bite was more powerful than usual, indicating that it has gained the dark type. Moreover, it took much less damage than expected from Wild Charge, which proves that it is no longer of dual water and flying type. X's answer puts a grin on Lysandre's face, and he compliments the boy for his analytical mind.

While Elec and Mega Gyarados take a brief break from each other, the two other pairs continue their fight, and Pyroar keeps pawing at Kanga menacingly. Xerosic can see that Pyroar's fiery breaths which could reach 10,000 degrees Fahrenheit are getting too much for the baby Kangaskhan to bear, and watches as Li'l Kanga retreats deep into its mother's pouch. Kanga attempts to throw a punch at Pyroar, but the fire lion digs its fangs into Kanga's arm and topples the Kangaskhan over with a head thrust. Kanga crashes into X and Lasma, and the boy struggles to climb back onto his feet as he catches his breath.

Lysandre finds it odd that X still has not Mega Evolved his Pokémon, but thinks he shouldn't let down his guard since the boy is definitely up to something. Xerosic observes that their Boss is clearing having the upper hand in all three match-ups, and wonders if they have overrated the boy and shouldn't have named him as a chosen one like them after all. At that moment, a warning siren goes off, and Xerosic gasps in shock that it is the low power alarm. Lysandre is taken by surprise as well, and notices that X has apparently peeled off the tape covering his Keystone, which implies that the boy has already Mega Evolved a Pokémon. Before he could figure out what is going on, Li'l Kanga lands from mid-air onto Mega Gyarados head, and stomps hard onto its face, causing it to writhe in agony. Xerosic realizes with a start that it was Kangaskhan which the boy has Mega Evolved, but they weren't aware of it because only the baby changes appearances while the mother stays the same. Feeling stumped, he grunts in frustration, but believes that his top priority is to find out why the Absorber's power level has dropped.

Lysandre compliments X's tactics, but wonders if it is really worth trading Mega Manectric's super effective type matching for the surprise factor. Just then, the Absorber shuts down, and Lysandre demands to know what is going on. Xerosic explains that the insufficient power has caused the Absorber to stop, and notices that Xerneas's bioenergy has yet to be drained completely. In fact, the 'Tree' has started to glow softly for some unknown reason. The Team Flare Boss soon realizes what X has done, and finally understands why he didn't Mega Evolve Manectric. It turns out that the boy has been utilizing Manectric's Lightning Rod ability to take away the Absorber's electricity, draining it of its power.

X scoffs at Lysandre's accusation that he 'took' the Absorber's power, since it was Team Flare who 'took' away other people's electricity to start with. Clearly, half of Lumiose City suffered from a black out because its electricity has been taken away to power up this Absorber device, and right now, he is simply returning the favour. As X speaks, the 'Tree' begins to glow increasingly brighter, and finally results in an explosion of light. To everyone's shock, Xerneas reverts to its true forme, and steps off from the Absorber. X wears a look of relief on his face, and looks up at the mighty deer as it towers over him.

Meanwhile, at the Laverre Hospital, Y sits at Grace's bedside, and takes the hand of her unconscious mother into her palms. Having changed back into her repaired flying suit, she tells Grace that she shall set out soon, and states that although she never said it, nor was she even aware of it, she truly respects her, and thanks her for raising her as a Rhyhorn Racer. She apologizes for being so antagonistic all this time, and a tear drop rolls off from her cheek. At that moment, Shauna appears at the doorway, and tells her to hurry since the Gymleaders are about to depart. Y replies that she is ready, and wipes her eyes dry as she leaves her mother's side.

Outside, Trevor and Cassius stand on the cliff and watch as the five Gymleaders set out from the western coast. Earlier, after learning that X has gone off to Geosenge, where Team Flare's headquarters are most probably situated, Trevor has relayed the information to the Grant, Valerie and Olympia. Not long after, the Coumarine Gymleader Ramos and Snowbelle Gymleader Wulfric arrived, and the five Gymleaders eventually decided to use Wulfric's Avalugg to approach Geosenge by the water route.

Valerie waves joyfully to Trevor as Avalugg begins to sail off, but Y, Shauna and Tierno arrive at that moment and request the Gymleaders to wait up. Y hopes that they could come along, and Shauna scolds Trevor for just sending the Gymleaders off like a dope. Wulfric wonders who the kids are, and Grant explains that they were the ones from Vaniville whom he mentioned. Recalling their story, Wulfric quickly understands their eagerness, and believes that their anger and frustration are powerful motivations which would surely make them dependable comrades and battling forces. He tells them to get on, but Y says only Trevor, Tierno and Shauna would need a ride since she shall fly on her own. Just then, her Rhyhorn, which has dropped the tent it has been carrying all this time, approaches her, and she retreats it into its Pokéball. She is determined to win, and looks forward to see the true strength of Rhyhorn, whom she has nicknamed Rhyrhy. With that, the Sky Trainer gears herself up and leaps off the cliff, while her friends set out with the Gymleaders on Avalugg.

Back at the Team Flare Secret HQ, Xerosic bolts with bewilderment that the legendary Pokémon Xerneas has awakened from its dormant forme. However, Lysandre believes that there is nothing to worry about, and tells Xerosic to take note of the color of its antlers. The Scientist only then realizes that they are blue, which means that it is still in its Neutral Mode. He understands his Boss's indifference, since there is nothing to fear if Xerneas has not entered its Active Mode. Lysandre wants to know if the bioenergy absorbed into the Ultimate Weapon is adequate for its activation, and Xerosic checks that it is currently at 70%, which should be more than adequate. The news delights Lysandre, and Mega Gyarados uses its tail to propel him up onto a small platform suspended from the ceiling, which is attached to a cubic machine that has what appears to be a keyhole. Lysandre pulls out an oddly shaped key to fit into the opening, and proceeds to unlock it, which happens be the way to activate the Ultimate Weapon.

Immediately, the whole town begins to tremble, and the three stone pillars that stand at the town center slowly regress underground. In the air, Bryony watches as smoke rises from the three openings where the stone pillars were, and before long, the entire ground crumbles into pieces as a gigantic multi-coloured crystalline structure breaks out in ascent, toppling all the houses around it. Towards Geosenge's western coast, Avalugg approaches from a distance, and everyone on board is shocked by the explosive emergence of the structure. Wulfric gasps that it must be the Ultimate Weapon, and Valerie states that although it sounds wrong, it looks strangely beautiful. The same thought actually goes through Trevor's mind the moment he sets eyes on the structure. However, he could barely say a word and simply wears a bewildered look as he stares at it.

The Ultimate Weapon soon emerges from underground completely, and slowly begins to open up. Wulfric hollers that they must stop it before it fully blooms, and orders Avalugg to move quicker. He asks if Olympia can suppress it with her psychic powers, and the Anistar Gymleader says she will try her best although it may be difficult. At that moment, Shauna and Trevor notice that Y is speeding towards the Ultimate Weapon, and wonders what she plans to do. The Sky Trainer throws herself against one of the petals, and starts to hold it back with all her might. She grunts that she has no idea how to stop it, but shall not give up until she uses up all her strength. Her determination moves everyone else, and they decide to follow suit as they call out their Pokémon and throw themselves towards the Ultimate Weapon as well.

Nearby, Bryony watches as the Vaniville kids and Gymleaders try hard to suppress the 'Flower Petals' from blooming, and finds their act futile...