In the footage, Ash and the others landed in the forest. Appearing directly in front of them was a massive, warped tree covered in a thick layer of dark sludge, its branches thrashing and swaying wildly like writhing tentacles.
The moment any of the surrounding healthy vegetation came into contact with this polluted growth, it was instantly corrupted, morphing into extensions of the massive structure and causing it to swell even larger!
This filthy, anomalous tree was a localized manifestation of the residual negative energy within the Kalos region.
"I didn't expect to encounter one of these things the second we arrived! It's been nearly a year; has Greninja still not been able to completely eradicate them?"
A cold sweat broke out on Clemont's forehead. The sheer devastation brought upon Kalos by the Megalith and the giant roots during the team's past adventures was still fresh in his memory. It had taken their collective, maximum effort to put an end to it—yet that had only been scratching the surface.
"It's not that simple. If these things could be dealt with so easily, I would have brought Greninja back home with me a long time ago... The fact that he's still patrolling this forest means his mission isn't over yet!"
Ash pressed down the brim of his cap and unclipped a Poké Ball from his belt. "Since we're here, we're definitely going to help him out! Lucario, I choose you!"
With a brilliant flash of white light, Lucario materialized in front of Ash. His eyes locked onto the pulsating negative energy tree, and an instinctive wave of disgust welled up deep within his chest. It felt as though this corrupt entity were fundamentally antithetical to his very existence.
"Lucario, let's charge in and cut it down! Use Aura Sphere!"
At Ash's command, Lucario brought his paws to his waist, rapidly condensing a swirling ball of deep blue energy before launching it forward with a sharp cry! The sphere of azure light sliced through the air, generating a sharp, whistling wind as it sped toward its target.
But just as the Aura Sphere was about to impact the trunk, a thick, polluted root erupted from the earth directly in front of the tree, swatting the projectile aside like a fly!
Boom!
The deflected Aura Sphere detonated against a nearby clearing, carving out a massive crater. Ash and Lucario exchanged a brief, stunned look before their faces grew solemn. This corrupt growth was far more resilient than they had anticipated.
"Ash, let me help too!" Clemont offered, reaching for his own Poké Balls.
Ash extended an arm to stop him. "No need, Clemont. Our helper is already here!"
Before Clemont could ask whom he meant, a sleek, blue figure descended like a shadow from the canopy, landing gracefully right in front of Ash!
The newcomer stood tall with his arms crossed confidently over his chest. His skin was a deep shade of blue, and a long, light-pink tongue was wrapped around his neck like a scarf.
"Greninja! You made it!"
"Ko-gai!"
The newly arrived Pokémon was none other than Ash's absolute ace from his journey through the Kalos region—Greninja!
The sensory connection between trainer and Pokémon was entirely mutual; just as Ash could perceive Greninja's presence through his Aura, Greninja could sense Ash's distinct wavelength approaching.
When Ash first stepped into the forest, Greninja had already felt his arrival, but he had been in the middle of clearing out another pocket of negative energy elsewhere.
The moment he finished his task, he realized Ash had halted nearby, directly in front of a particularly massive growth of corrupt energy. He had sprinted across the forest without a single moment of delay, arriving just in time to back his trainer up!
Lucario stared intently at the confident Greninja, a highly complex expression flashing through his eyes. From this new arrival, he could sense an incredibly familiar presence.
It wasn't that they belonged to the same species, but rather that Greninja's relationship, chemistry, and history with Ash mirrored his own!
Lucario's instincts whispered that this frog possessed an incredibly deep, sacred bond with Ash—one that had been forged long before they had ever met.
A subtle trace of competitive jealousy flared within Lucario's chest. Greninja's role in Ash's life overlapped almost perfectly with his own. He could even sense a distinct, powerful ripple of Aura-like energy emanating from him...
"Let's go, Greninja!"
"Ko-gai!"
Ash and Greninja simultaneously raised their hands. Instantly, a massive vortex of spiraling water erupted around both of them in perfect synchronization, converging into a towering column of water that shot straight into the sky!
The swirling water surrounding Greninja shattered outward, condensing into a massive, high-velocity water shuriken pinned securely to his back. His physical form shifted, his features sharpening into a striking, heroic design that subtly mirrored the hairstyle and coloration of Ash's cap!
This was Greninja's legendary Battle Bond form!
"Water Shuriken!"
Ash reached his hand behind his back, gripping the empty air in a throwing motion before hurling it forward with absolute force! Greninja's physical movements mirrored Ash's perfectly.
He drew the massive Water Shuriken from his back and flung it forward, the azure weapon spinning at blinding speed as it tore through the air!
The negative energy tree attempted to repeat its previous defense, raising a thick, blackened vine from the ground to intercept the incoming projectile.
However, the moment the vine made contact with the high-speed, pressurized edge of the Water Shuriken, it was instantly sliced to ribbons!
Meeting absolutely no resistance, the shuriken struck the core of the giant, corrupt tree with pinpoint accuracy! After a brief, tense pause, the massive trunk let out a loud, groaning crack before completely withering away.
The slimy, corrupt roots spreading across the clearing dried up in an instant, turning into harmless, brittle twigs.
Greninja had completely eradicated the growing threat in a single, effortless blow—a target that Lucario's Aura Sphere hadn't even been able to scratch. The stark contrast in their performance made Lucario's previous attempt look completely ineffective.
With a soft glow, Greninja's form reverted to his standard state. Watching this miraculous display for the very first time, Chloe's eyes went completely wide with astonishment.
"What... what on earth was that? Can Greninja perform Mega Evolution? I'm certain my father's extensive research on Mega Evolution never listed Greninja as an eligible species! And if Ash can Mega Evolve his Greninja, why doesn't he have a Key Stone?
For that matter, why did the transformation look so completely different from standard Mega Evolution?"
For other trainers, Mega Evolution required the physical resonance of a Key Stone and a Mega Stone, enveloping the Pokémon in a sphere of genetic energy before transforming their shape.
But with Ash's Greninja, the process began with a massive torrent of water shooting into the sky, and Ash's physical movements had been completely synchronized with his partner's!
A barrage of questions overloaded Chloe's mind, leaving her completely bewildered.
"Haha, let me clear up some of those questions for you~" Clemont chuckled, seeing Chloe's utter state of shock. He stepped forward to explain the unique nature of the Battle Bond phenomenon.
"...What?! He can trigger an evolutionary shift without a Key Stone or a Mega Stone, purely through the sheer intensity of their mutual trust?!"
Chloe's pupils dilated in absolute shock. It turned out that alongside Mega Evolution, Z-Moves, and Gigantamax, there existed a highly specialized, singular evolutionary path unique to Ash and his partner!
"Lucar!"
Before Chloe could ask any further questions, a sharp bark cut through the air. Lucario was staring intently at Greninja, shifting his weight from side to side while aggressively flexing his fists. His intentions were perfectly clear—he wanted a battle right here and now!
...
Global Forum Chat Board
[Caitlin]: Is Lucario... feeling jealous?
[Cynthia]: Hehe, it's highly likely~ After all, Greninja and Lucario share an immense amount of conceptual overlap!
[Cynthia]: Unlike Pikachu or Charizard, the fated meetings of Greninja and Lucario with Ash carry an air of destiny. Ash, as a modern-day heir to the Aura Guardians, has forged bonds that transcend standard trainer-Pokémon relationships. Both of these Pokémon possess unique, power-amplifying states linked directly to Ash's spiritual wavelength—Greninja has the Battle Bond, while Lucario utilizes Aura Resonance.
[Cynthia]: Because their roles are so structurally similar, it's completely natural for Lucario to view Greninja as a direct rival! Of course, Ash and Pikachu's bond is also fated, but their connection operates on a completely different emotional spectrum that is difficult to put into words.
[Volkner]: I agree! When Champion Cynthia lays it out like that, it makes perfect sense. The mechanical and thematic similarities between Greninja and Lucario are incredibly high! No wonder Lucario is eager to test his strength.
[Diantha]: However... the Lucario of that specific period is simply no match for Greninja. Even if Greninja remains in his base form while Lucario utilizes his Aura Resonance, Lucario still lacks the combat experience to close the gap.
[Lance]: Indeed. You can easily deduce the disparity in raw power from how effortlessly Greninja dismantled that negative energy core just now.
[Siebold]: On that note, speaking of that strange growth, Ash referred to it as a 'Kalos negative energy core'. Since when did our region harbor such hazardous anomalies? And is this corruption the true reason why Ash had to leave Greninja behind in the wild?
[Diantha]: I am currently unaware of these specific root systems... I will immediately commission an elite task force to investigate our deep forests. If the simulated footage is accurate, a catastrophic future crisis in Kalos is directly linked to these negative energy manifestations!
[Drasna]: Oh, we are finally seeing a tangible clue regarding the crisis. It seems both Greninja and Lucario possess the unique ability to locate the structural weak points of these negative energy roots?
Drasna had keenly observed that both Greninja and Lucario had targeted the exact center of the root mass. The moment Greninja's Water Shuriken pierced that specific focal point, the entire structure instantly withered away.
[Professor Oak]: Exactly. It appears that the spiritual power of Aura is the key to detecting the core of these negative energy root systems.
[Professor Oak]: This hypothesis holds significant weight. If a trainer attacks the physical branches instead of the core, the root system will simply regenerate indefinitely. Even if you spent an entire day slicing at the vines, you would never be able to permanently destroy it.
[Professor Oak]: This perfectly explains why Greninja—who possesses a highly specialized sensory connection to the earth's natural energy—needed to remain in Kalos to protect the region! And Lucario, wielding active Aura, can also perceive these cores. Along with Ash, all three of them share a deep, functional mastery over Aura-class energies!
[Diantha]: In that case, couldn't we simply deploy a group of trainers partnered with Lucario to assist in clearing the forests?
[Professor Oak]: While that sounds practical, standard Aura manipulation might not be the sole requirement. There seems to be a far deeper common denominator between these three...
Backyard of the Oak Research Laboratory:
While Professor Oak was deeply lost in thought, the young Riolu standing in the yard had quietly padded over to Ash's Froakie.
"Rio! Riolu!" (I came to our trainer's side at the exact same time as you, so there's no way I'm going to let myself fall behind you like the Lucario in the video!)
Froakie narrowed his eyes slightly, offering a casual, cool response. "Kero~" (If you're so confident, we can always settle this in a battle once this broadcast finishes.)
"Rio!" (I wouldn't have it any other way!)
While the humans were deeply engrossed in analyzing a potential regional catastrophe, the two young Pokémon destined to help resolve it were already sparking a fierce, healthy rivalry of their own. Even Ash hadn't noticed their quiet interaction, his eyes completely glued to the screen as the impromptu duel between Lucario and Greninja began to unfold!
In the Footage—
Faced with Lucario's eager challenge, Greninja did not decline. He simply crossed his arms, standing tall and perfectly balanced as he calmly locked eyes with the younger canine. His tranquil gaze carried a silent, clear invitation: Show me what you've got. You can have the first move.
"Lucar!"
With an explosion of physical speed, Lucario's figure blurred, vanishing from his position instantly! Utilizing Extreme Speed, he closed the distance between them in a fraction of a second, appearing directly in front of Greninja.
Without hesitation, he rapidly condensed a highly pressurized Aura Sphere in his right paw, thrusting it forward with maximum force! The swirling blue projectile crackled with violent, dense energy waves; Lucario was clearly holding absolutely nothing back!
Yet, throughout the entire lightning-fast sequence, Greninja's expression remained completely serene.
With a subtle, incredibly fluid tilt of his upper body, he effortlessly slipped past the path of the oncoming strike. Moving with absolute economy of motion, he delivered a swift, precise tap to the side of Lucario's neck.
Lucario's pupils contracted in instant shock. The Aura Sphere in his grip dissolved into thin air as his knees buckled, sending him half-kneeling onto the grassy earth.
That seemingly effortless, feather-light strike had carried enough precise force to nearly knock him unconscious! The sheer disparity in their combat experience was plain for all to see.
"Lucario, that's enough! Stop!" Ash quickly stepped in to de-escalate the tension. "Greninja is an incredibly seasoned veteran who has fought through countless high-stakes battles. You've only recently evolved, and you haven't reached the level of maturity and physical growth that he possesses yet!"
It had taken Ash a moment to recover from the sudden clash before he managed to intervene. Greninja had not only journeyed alongside him through the entire Kalos League, but he had spent nearly a year honing his senses under the guidance of Zygarde.
For the current Lucario, securing a victory in a standard sparring match was a mechanical impossibility—unless, of course, they actively tapped into their synchronized Aura Resonance state, which might have granted them a narrow fighting chance.