Japanese Title: The Advancing Megalith! The Kalos Line of Defense!!
Original Airdate: September 15, 2016
US Airdate: November 4, 2016
What? You think we would sit out during a crisis!?
Mairin and Serena's efforts to save Chespie are in vain as it is absorbed by the giant rock, becoming the power source for Megalith Zygarde. Ash, Alain, the Kalos leaders, Malva, Sycamore, Steven, and Diantha rush to stop the megalith before it is too late.
This episode contains examples of the following tropes:
- Apocalypse How: The collision between the Megalith and the Anistar Sundial will cause a Type X, where Steven hypothesizes a World-Wrecking Wave will wipe out all life on Earth.
- Better to Die than Be Killed: With both of his Pokémon defeated and Team Flare's plan to control Zygarde up in smoke, Lysandre jumps off the Prism Tower rather than surrender to the heroes. Subverted, as it turns out he survived.
- Big Damn Heroes:
- Charizard X and Pikachu swoop in at the nick of time to save Serena's Braixen from falling to her death.
- The Cavalry rescue the heroes when the Megalith had all of them trapped in its grasp.
- All the gym leaders show up in time to assist our heros.
- The Bus Came Back: Every Kalos Gym Leader (at least the ones Ash has fought) and their ace Pokémon return to defend the Anistar Sundial. Notably, this is also the first time all eight Gym Leaders appear together in an episode.
- Call-Back:
- Steven's hypothesis brings up established facts about the Megalith and the Anistar Sundial.
- Korrina and Olympia compliment Ash on his Ash-Greninja; the former heard about it through rumors (making Ash-Greninja reach Famed In-Story levels) and the latter because she was the one who predicted the whole thing in the first place.
- The Cavalry: The Kalos leaders, led by Olympia and Diantha, rally to the badlands to help fight the Megalith.
- Expy: Upon transforming, the Megalith shares quite a few similarities with the fake Groudonnote .
- Futile Hand Reach: Variant, where Ash frantically had Greninja use his Overly-Long Tongue to try to snatch Lysandre before he jumps the Prism Tower. He missed by a few inches.
- Mythology Gag: The Cavalry of Gym Leaders during the climax of the conflict is similar to what happened in the Black and White games, where the Unova Gym Leaders come to the player's aid after Team Plasma launched their attack on the League.
- Powered by a Forsaken Child: Chespie is the power source for Megalith Zygarde.
- Your Princess Is in Another Castle!: Serena's group thought that rescuing Chespie from Lysandre Labs is all that was needed to be done.
