"Greninja, the Ninja Pokémon. Type: Water/Dark. It appears and vanishes with a ninja's grace. It toys with its enemies using swift movements, while slicing them with throwing stars of sharpest water."

Verdant Cavern (Day)

"So, this is a Totem Pokémon." Dominic said as he looked up at the towering form of Totem Gumshoos. From what his Rotom Dex told him, they were typically much smaller. 'Hala said that Totem Pokémon were blessed by the Island Guardians. Maybe this is what he meant.'

Totem Gumshoos got down on all fours and roared loudly, shrouding itself in an energy resembling Z-Power. It then stood upright again, waiting for its opponent to bring out his Pokémon.

"Okay, this is a battle to determine whether or not I can use Z-Moves." Dominic told himself as he brought out a Poke Ball. He looked down at the Z-Power Ring on his arm. "Tapu Bulu may have given me this gift, but I haven't earned the right to use it until I manage to obtain a Z-Crystal for myself." Smiling, he pulled his arm back. "So, let's give this battle our all, Greninja!" Throwing the ball, he released the only Pokémon he brought with him to Alola.

In a burst of light, the Ninja Pokémon appeared. Totem Gumshoos looked at its opponent, sizing it up. Smirking, it started the battle by clawing at the ground and throwing fistfuls of dust into the air, causing a sandstorm. Greninja raised its arm, protected its face from the sand.

"This won't be like other battles." Dominic said, thinking of a strategy. "Start with Dark Pulse!" Greninja made a series of rapid hand-signs before firing a beam of negative energy, landing a direct hit on Totem Gumshoos. When the smoke cleared however, it didn't look injured at all. "Okay, that's going to make things difficult."

Putting a paw on where Dark Pulse struck it, Gumshoos made a decision. It roared into the air, creating an echo that reverberated through the cave. After a few moments, a wild Yungoos ran to the Totem Pokémon's side.

'I've heard about this.' Dominic thought to himself as Yungoos bared its teeth. 'Professor Kukui said that sometimes, wild Pokémon will call their allies for help. If I'm going to win, I'm going to have to beat both of them.' The blonde smiled at the idea of an entire Region filled with these kinds of battles. "Greninja, don't let yourself be intimidated by the disadvantage. You're strong enough to take both of them on!" Greninja nodded, its pink eyes burning with conviction. "Use Water Shuriken on Yungoos!"

Yungoos jumped forward, biting aggressively. Greninja leapt out of the way just in time, compressing the mucus on its thighs into throwing stars before throwing them at the smaller Pokémon. Two of the five attacks landed, thankfully being enough to deplete Yungoos' HP.

"Way to go, Greninja! Just one more to go!" Dominic cheered. That's when he noticed something strange about his partner's body. It was...glowing. In a bright blue light, Greninja's body became shrouded in a cyclone of water. 'What's happening!?' the trainer asked himself. 'Is this Greninja's Ability?'

As strange as it was, Frogadier's Evolution into Greninja somehow made its Ability vanish. By process of elimination, he knew it wasn't Torrent or Protean. Since Greninja couldn't have any other Abilities, he assumed that the Pokémon had lost its Ability. But maybe he was wrong. Maybe he had discovered a new Ability that only Greninja could possess.

Within the vortex, Greninja's form slowly changed. A red crest appeared on its head, and black spikes resembling hair appeared on its horns. It also gained a pattern on its chest that looked eerily similar to the first jacket Dominic bought in Kalos. But the biggest change was the giant Water Shuriken that appeared on its back. After the transformation was complete, the vortex disappeared.

"I can analyze this later. For now, the priority is the battle." Dominic told himself, relishing at the thought of a new research subject. "Use Gunk Shot!" What happened next was a surprise for everyone involved. At indescribable speeds, Greninja vanished and reappeared behind Gumshoos with an orb of toxic energy in its hand. The Totem Pokemon barely had a chance to turn around before it was attacked with the Poison-Type Move. The force of the impact also sent Gumshoos flying into a wall.

After the attack, Greninja looked down at its hand, shocked by the amount of power it now had. Was its Ability only showing itself now because it was in Alola, or was there another reason behind this strange transformation? Regardless, this power would be useful if the battles in Alola were only going to get harder.

"So, this transformation comes with a drastic increase in power and speed." Dominic noted. "And it appears the catalyst for this Ability is when Greninja knocks out an opposing Pokémon." Hearing the sound of stones moving around, the blonde turned to where Totem Gumshoos was. It was slowly getting back on its feet.

The Totem Pokémon's eyes turned red as it rampaged around, running at full speed towards Greninja. It wanted to defeat the challenger and his Pokémon with a single attack. It didn't have the energy to do anything else.

Seeing the expression on Greninja's face, Dominic knew that it wanted to use a particular Move. "Alrighty then! Let's end things with Water Shuriken!" he commanded. Greninja grabbed the shuriken on its back, then threw it at the rampaging Gumshoos. The Water Shuriken was spinning so fast, it resembled a disc more than a throwing star. The attack landed, causing an explosion of water that made the ground crack.

Tired out, Totem Gumshoos fainted. Several Yungoos rushed to its side, carrying Oran Berries and other kinds of food they had stored. After a few moments, Gumshoos was back on its feet. It watched as Greninja reverted back to its normal form, still confused about what kind of power it had awakened.

"Looks like there's another benefit to this Ability." Dominic said. "In addition to the power and speed boost, Water Shuriken gains a massive increase in strength. Fascinating." The boy turned his attention to the pedestal in the center of the room. Walking over to it, he picked up the Normalium Z inside. "And with that, we've completed our first Trial, Greninja." He turned back to his Pokémon with a smile.

But as the duo left the cave, one thought ran through their heads. What exactly was the transformation Greninja went through, and why did it only show up now?