Go’s Scyther is indestriketible! <3
I can see Poipole staying til the end of the series especially if Ash could use it in battle (and I honestly want that adorable rolling top to stay). There's a reason why it's explicitly shown in Ash's rooster and being seen as Ash's Pokémon whereas with Nebby, we knew it was going to be involved in the Aether Foundation arc and mainly used as such. Poipole has the opening as the main focus and having it leave after an arc doesn't seem right like why let it be the main focus with lyrics describing it's feelings instead of side scenes? I want Poipole to be a breakout character where it'll stay with Ash until the end of the series. I can't see them catching all the Ultra Beasts that quickly and easily as they did with Buzzwole.Given that Lusamine told Ash to keep Poipole as his partner Pokémon until they find the Ultra Wormhole it used to get to Ash's world, I'm pretty sure it's safe to assume Poipole(/Naganadel, if it evolves) is going to be released by the end of the series, regardless of how well it bonds with Ash and his team. As much as I would love to see that bundle of giggling playfulness remain a permanent member of Ash's team, at the same time, I also feel it's more appropriate for it to be returned to its own world. If the writers do this right, they could turn that into an interesting and emotional story/character arc, for all of the characters involved.