“Pokemon the Series: Sun and Moon” was a big departure for the “Pokemon” anime (via Forbes), especially for longtime fans. Instead of spending the series touring the seventh generation Alola region, it instead follows Ash as he becomes a student at the Pokémon School and deals with the game characters Lillie, Mallow, Sophocles, Lana, and Kiawe, and Professor Kukui, their teacher , befriended. Despite this, there have been many mature approaches to the series, such as the Pokemon dying storylines (per Polygon).
Still, the series has its funny moments too, and gives Ash some pretty incredible performances to brag about. One of these occurs late in the series after Ash and his classmates discover the existence of Ultra Beasts. Similar to their roles in Pokemon Sun and Moon, Ultra Beasts are special Pokemon that come from another universe (according to Gamerant) and have powerful abilities and stats. Ash befriends one of these Ultra Beasts, the Venom-type Poipole, who allows Ash to capture him until they can return him to his homeworld.
Despite becoming close to Ash’s Pikachu, Poipole eventually returns to his own world, later reappearing in his evolved form Naga Nadel (via ComicBook), and temporarily becoming a member of Ash’s team. Naga Needle is even used by Ash during his championship fight against Kukui before he finally returns to his home world at the end of Pokémon The Series: Sun and Moon. However, it will always be one of Ash’s strongest and closest partner Pokémon.
