As someone said in a conversation about this.
People are going to count this as another loss if Ash loses. But those same people won't call this a legitimate win if he wins. And everyone agreed that it was ridiculous that it was going to be viewed this way.
I on the hand would only feel the win as meaningless if they decide to retire Ash after this generation because Ash did not deserve to retire after this horrible generation when it comes to development of Ash and his Pokemon. Oh yeah sure there's countless move learning and slice of life episodes but they served no real purpose but to be like "HEY at least we are trying" rather than give his Pokemon the development they deserve. Although if Best Wishes is anything to go by, they will ignore development for a cheap gag, yeah sure different writers different styles, but SURELY they talk to each other, right.
And even though Delia and Oak show up, Ash deserves proper closure, not just simply an end to the Alola region including past characters showing up, and perhaps a major battle tournament where Ash uses ALL of his Pokemon against people from his past. All culminating in a final Ash episode where Ash reiterates his dream to be a Pokemon Master and walks off into the sunset with Pikachu. Fin. Not a horrible rush job, just because Ash is the Champion of Alola and we don't care and we move on with something else.
But I will consider this a win for Ash regardless, it makes no sense to belittle Ash when Ash has shown to be (in regards to the league) the strongest trainer, with Gladion only edging above him (like rivals are supposed to be for the protagonist). We've constantly seen his battles and his progress MORE than any character in the show. And while I'm sure there are suspicious reasonings, like Lycanroc defeating all of Nanu's Pokemon only to lose to Gladion's Lycanroc later, which creates this weird power logic problem, but I guess it comes down to strategy there.
I mean there was never any reason for Gladion to even be as strong as he was, and likely only had strong Pokemon because of their inherently raw power (like he who will not be named's Pokemon in Unova) he even completed the trials AFTER Ash. True I do get that Hapu wasn't the Kahuna yet, but look at how long it took for Gladion to defeat her or to even challenge her (more accurately), either he was doing other trials or he actually did fail against her, OR even maybe he was too busy doing other things.
But being a rival shouldn't have been an excuse for Gladion to be as strong as he was. Sure there's the whole Lillie protecting concept, but the anime is very different than the games, some of that motivation is lost however, outside of a normal brother caring for his sister. Though I do wonder if Lillie's trauma kind of made up for not being abducted by Team Skull. But even still stronger than Ash? Like other trainers, sure, but Ash? Only because he's the rival?
That's why I think Ash deserves this, at the very least he deserves this because he only has to defeat Gladion, and I do think Gladion could be defeated by Ash if the writers would stop screwing him over. And if Ash defeats Gladion then he deserves to win the league.