Pokemon Sun and Moon: The Series is about to bring back another one of Ash's classic Pokemon. A new trailer for an upcoming two episode storyline has revealed that Ash will reunite with his Muk. In a short clip, Muk hugs Ash and almost entirely covers him with its sludge-like body.
Ash caught Muk after an encounter at a power plant, but quickly transferred it back to Professor Oak's lab because its stench permeated the PokeBall. Although Muk was antagonistic to Ash before he caught it, it turned into a very affectionate Pokemon who loved to hug both Ash and Professor Oak.
Ash used Muk in several Pokemon League battles, most notably against Jeanette Fisher's overpowered Bellsprout. While the Bellsprout took out both Bulbasaur and Pikachu with ease, Muk simply smothered Bellsprout to win the battle. Ash also used Muk in his battle against Gary in the Silver Conference, where it fought Gary's Blastoise to a standstill. Muk's last appearance was over five years ago, when it joined Ash and his Pokemon for a giant group picture shortly before Ash left for the Kalos region.
Ash is returning to Kanto in the upcoming two-part episode arc and reuniting with several of his oldest friends. Not only are Brock and Misty returning for the two part episode, but Bulbasaur and Jigglypuff are also confirmed to make an appearance. The upcoming episodes will also feature Ash trying out Pikachu's Z-Moves against Mega Evolved forms of Brock's Steelix and Misty's Gyarados. Ash's Alola classmates will join Ash on his trip and will get to see Kanto versions of several Pokemon for the first time.
The episodes will air over in Japan on September 14 and 21, and will eventually air on Disney XD, likely in late December or early January.