Character from pokemon-journeys by
Ash's Kalos partner returned -- the Water-type ninja that Bond Phenomenoned into Ash-Greninja, pulled back into service for the World Coronation Series.
Greninja is the most widely-travelled of Ash's old partners, having spent the years between Kalos and Journeys protecting the Kalos region from smaller crises with Squishy the Zygarde. When Ash calls it in for the Masters Eight, it arrives via teleport-shadow without a word and slips into the line-up like it never left. In battle it relies on Water Shuriken, Double Team, Cut, and the Bond Phenomenon that lets Ash see through its eyes and share damage with it. The bond still works; Ash still feels its hits. Under pressure Greninja goes still, drops into Bond form, and dictates the fight's tempo. It is the Pokémon most visibly proud of Ash's climb.
A tall bipedal Water-type ninja-frog with dark blue skin, pale yellow eyes, a long tongue-scarf trailing from its neck, and delicate webbed fingers. In Bond Phenomenon form it takes on a water-shuriken crown and Ash's cap silhouette, with red stripes echoing Ash's face markings. Moves silent and quick, drops into shadow at the edge of scenes.