Mash the Demon Shark

"Mash the Demon Shark" is the fortieth and final episode of the third season of Pokémon Strange Journeys, and the one-hundredth-eighty-fifth episode overall. It aired on September 23, 2016.

Plot
Mash returns from the ocean and suddenly transforms into a demon-like shark with red eyes, and it's up to Ash and his friends to fight her.

At the end, the gang finds a portal and go into it, which leads into "The Ghibli Saga".