With his match against Raihan coming up, Ash has his team training hard in preparation. During a short break, Goh's Froakie gets into a sparring match with Chloe's Eevee, causing it to evolve into Frogadier. Inspired by this turn of events, Ash decides to take Lucario to Kalos to meet up with the Greninja he left behind, letting The Ace of the XY era teach the successors of the Journeys era.
This episode contains the following tropes:
- Always Someone Better: Greninja demonstrates that it's leaps and bounds better than Lucario when they have a battle against each other. Lucario doesn't even land a hit!
- Bait-and-Switch: When Ash asks Greninja if it's willing to help train Lucario, it appears to walk away...only to turn around and agree with an appropriate Bring It gesture.
- Broad Strokes: While the episode sets up the opportunity for Ash-Greninja to reappear, it only does so in spirit. Rather than the form being seen, Ash only describes his bond with Greninja as a constant one, sensing each other's movements in battle and being connected together despite having parted. Even the flashbacks where it might have appeared are changed to only show Greninja as normal.
- The Bus Came Back: After being released at the end of the XY series, Ash's Greninja returns so its old trainer can ask for its aid.
- Call-Back:
- Ash recounts how he first met Greninja back as a Froakie, how they trained together to get stronger, their brief falling out and reconciliation, their time in the Kalos League, and their eventual parting of ways.
- The deadly roots left from Lysandre's attack on Kalos are still causing havoc, and Ash, Greninja, and Lucario all battle against two of them. However, Ash doesn't explain what the roots are.
- Curbstomp Battle: Greninja wallops poor Lucario so badly without even getting touched.
- Determinator: Raihan is bent on making sure he can defeat Leon, and trains so hard off-screen that he and Duraladon are both deeply exhausted, but nevertheless press on so he can keep Ash from advancing into the Masters Eight.
- Epic Fail: Lucario's battle against Greninja goes so poorly, it even fails to Mega Evolve.
- "Eureka!" Moment: When Goh's Froakie evolves into Frogadier, Ash gets the idea to go see his Greninja, convinced it could give Lucario a few pointers.
- Hot-Blooded: Deconstructed. Lucario may be The Ace of Ash's team now, but its desire to battle and lack of patience leads to Greninja flattening it in a battle. Even attempting to Mega Evolve falters, as Lucario is simply too angry. It takes a lesson from Greninja in balance and patience that helps Lucario to truly master its aura.
- Once Done, Never Forgotten: Invoked by Raihan, who kept a picture of him with a disappointed look on his face after losing to Leon, so he can remind himself never to feel like that again.
- Not So Above It All: As a sign of its Character Development, the normally serious Lucario gives Ash a big old hug as thanks for its trainer helping it to master its aura.
- "Not So Different" Remark: Goh and Ash both note that Lucario and Greninja are a lot alike in that both wanted to become stronger.
- Sore Loser: Lucario storms off angry that Greninja trounced it. When the frog follows, Ash decides to leave it be, trusting his old friend enough to help set things right.
- Took a Level in Badass:
- Goh's Froakie evolves into Frogadier.
- Thanks to Greninja, Lucario is able to focus its Aura Sphere into a Spirit Bomb. This is best shown when fighting the roots; it couldn't land a scratch on the first one, but it demolishes the second one with Ash and Greninja's help.
- Training Montage: All of Ash's team are shown training at the beginning of the episode as they spar with one another.
- What Happened to the Mouse?: Despite Greninja still being on its mission to rid Kalos of all the roots that Lysandre created, neither Squishy or Z-2 put in an appearance proper, nor does Ash mention them.
- The Worf Effect: Lucario may be The Ace of Ash's current team, but Greninja demonstrates it's a far better fighter by dancing around Lucario and giving it a Dope Slap during their battle.
