Pokemon Sun & Moon - episode 100 - 08 Dec, 2018

While training for a possible Poni Island Grand Trial, Ash and Pikachu once again encounters Tapu Koko and ask it for a battle. The clashing electric attacks create a portal that drags Ash and Pikachu into a mysterious world, one which has been destroyed and left in ruins. They discover that this is the world of the mysterious Ultra Beast, Guzzlord. Guzzlord attacks them, but a mysterious trainer and a Zeraora comes to their rescue. (Source: Wikipedia)