Just like the first stage of their Shuriken Throwing Training, during the second stage—Practical Combat Training—Ash and Greninja's heart rate synchronization once again stalled after reaching the 90% mark, falling into another bottleneck.
Fortunately, Ash had already planned beforehand how he would achieve complete unity between Trainer and Pokémon during the second stage of training.
That plan was the psychic power he possessed—Aura Power.
Aura Power was a mysterious force born from one's soul that inherently possessed the ability to connect hearts and minds. Half a year ago, during Professor Oak's Pokémon Summer Camp, Ash had once silently directed Serena in battle through Aura Power.
Later, after the Summer Camp ended and Ash officially received his own Pokémon before beginning his journey of battling at the City Arena, he had similarly demonstrated his ability to silently command his Pokémon through Aura Power before the public.
However, as both Ash and his Pokémon had continued growing stronger, they rarely encountered Trainers capable of defeating them, even without resorting to their hidden trump cards.
Thus, over time, Ash had seldom used Aura Power for silent command during official battles.
But not displaying it publicly did not mean he had forgotten that he possessed such an ability.
No one understood the capabilities of Aura Power better than Ash himself.
Aura Power could establish a connection between Trainer and Pokémon, allowing both sides to sense each other's emotions and intentions. For achieving the goal of complete unity during practical combat training, it was practically a bug-level support ability.
Although Aura Link merely allowed Trainers and Pokémon to communicate instantaneously, share sensory perceptions, perceive each other's battlefield perspectives, and understand what the other was thinking in that moment, it couldn't directly make their hearts become one.
At most, it provided them with vital information and the necessary conditions to achieve that goal.
And that alone was already extraordinarily powerful.
When both Trainer and Pokémon could clearly perceive one another's thoughts, the difficulty of achieving complete unity would immediately decrease by well over ninety percent.
Had Ash not been worried that both he and Greninja might become overly dependent upon Aura Power, he would have used it during the very first stage of their Shuriken Throwing Training.
Thankfully, he didn't.
Instead, he waited until their Unity of Hearts training had completely gotten onto the right track before finally activating Aura Power after they encountered a bottleneck during the critical second stage of training.
...
And sure enough, with Aura Power providing assistance, their previously stagnant training began moving forward once again.
The heart rate and electrocardiogram synchronization that had been steadily stuck at ninety percent during combat rapidly rose to one hundred percent.
The objective of the second stage of training had finally been achieved.
"Greninja—"
Ash didn't even need Rotom to announce it this time. The moment he and Greninja achieved complete unity, he instinctively felt the change himself.
"Gren! (ー_ー)"
Seeing Ash look toward him, Greninja nodded knowingly in response.
At this moment, their hearts were perfectly synchronized. Naturally, Greninja understood exactly what Ash was thinking.
"GREN—!!"
With a powerful battle cry, Greninja followed the instinctive guidance flowing from deep within its body as the hidden potential sleeping inside it was finally awakened.
The powers of Water and Dark coursed throughout its body, perfectly intertwining before transforming into a surging black tide of energy.
BOOOOM!!
The immense power raging within Greninja's body was simply too vast and too violent. Unable to be completely contained, part of it overflowed outward, transforming into raging torrents of water that enveloped Greninja's entire body.
At this moment, Greninja seemed to be wearing an armor of swirling water.
Its entire body was protected within a raging aquatic cyclone, while standing proudly at the very center of the vortex, exuding an incomparably majestic and imposing aura.
"Greninja—"
Ash glanced toward Greninja. The Bond-Evolved Greninja seemed overflowing with limitless power.
And Ash himself felt exactly the same.
"Gren!"
Within their perfectly synchronized state, no lengthy explanations were necessary—Greninja had already understood everything.
The battle that had momentarily paused erupted once more.
Wrapped in raging torrents of water, Greninja launched itself toward Pikachu, who was serving as its sparring partner upon the gravel riverbank, with even greater speed and ferocity than before.
"Pika!!"
Across from him, Pikachu couldn't help but cry out in surprise.
The moment Greninja activated this brand-new [Bond Evolution 2.0], Pikachu immediately felt the overwhelming pressure radiating from its transformed companion.
Previously, the two had been evenly matched. In fact, thanks to its slightly higher level, Pikachu could even suppress Greninja to some extent.
But now that Greninja had entered Bond Evolution 2.0, Pikachu instantly felt an overwhelming sense of pressure rushing toward it.
"Pika~!"
Seeing Greninja charging toward him like an unstoppable storm, Pikachu didn't hesitate in the slightest. Raising his paws, he immediately erected an energy barrier—Reflect.
BANG!!
The speed of Bond Evolution Greninja far exceeded even Ash's expectations.
The instant Pikachu raised his protective barrier, Greninja had already appeared before him and sent him flying with a powerful kick.
"PIKACHUUU!! (>A<)"
Pikachu cried out as his small body was kicked away like a soccer ball.
However, Pikachu was far from an easy opponent to defeat.
As Ash's original partner Pokémon and a child of destiny among Pokémon, Pikachu's strength was something few could ever hope to imagine.
Although he had been sent flying by Greninja's kick, the barrier created by Reflect remained intact. Even while airborne, Pikachu had already adjusted his center of gravity and reinforced his shield to continue enduring Greninja's relentless assault.
BANG!!
BANG!!
BANG!!
...
Bond Evolution 2.0 Greninja was unquestionably powerful.
Its speed was especially terrifying.
Although it couldn't shatter Pikachu's protective barrier with a single strike, its relentless attacks came down like an endless hurricane, leaving Pikachu without even the slightest opportunity to retaliate.
At this moment, Greninja resembled a living torrent of water ricocheting wildly across the gravel riverbank.
Meanwhile, Pikachu could only endure the assault. Maintaining his protective barrier, he was kicked back and forth repeatedly like a bouncing ball by Greninja.
The battle didn't last very long.
Although Greninja had completely suppressed Pikachu, it still couldn't defeat him decisively.
And once Pikachu managed to find an opening, Wish + Parabolic Charge would allow him to rapidly restore himself to full condition, dragging the battle into yet another prolonged stalemate.
Fortunately, Ash had only arranged this battle to test Greninja's newfound power.
After witnessing the overwhelming might of Bond Evolution 2.0, Ash called an end to the match.
He then proceeded to conduct more detailed tests upon Greninja's transformed state.
[Bond Evolution 1.0] = Twofold Enhancement
[Bond Evolution 2.0] = Threefold Enhancement
After completing the tests, they discovered that compared to Greninja's normal state, Bond Evolution 2.0 provided an astonishing threefold increase in all aspects of its overall abilities and combat power.
Such tremendous growth once again demonstrated the terrifying potential hidden within Bond Evolution.
The path that belonged exclusively to Greninja had only just begun.