Why would they dead give away that Brionne is evolving in the Kyogre episode, which people had debates about happening since it would take away from the Kyogre moment...
Not sure why that matters. The only reason the Kyogre episode would exist is to evolve Brionne if its evolving, the episode isn't about Kyogre its a Lana episode, which is precisely what most people thought, even implying Lana catching Kyogre, if not Kyogre than Primarina and it explicitly states something happens to Brionne, so I don't even know how the argument of "evolution would ruin Kyogre's appearance" would even remotely be valid. Sure "one" might like Kyogre far more than Lana evolving her Brionne, but that's not relevant to the actual process of them making an episode. You have to ask, if THEY care about Kyogre more than evolving Brionne, and I would argue at the moment that NO, no they don't.
yet not even give so much as a hint about Ash's Pokemon whatsoever? Even Togedemaru and Shaymin got hints of being better battlers then we give them credit for since they rarely battle at all in the first place.
While it could be a coincidence, it should be noted Pokemon Fan doesn't exactly reveal anything that we as fans couldn't speculate or guess based on the information WE have access to, the reason they gave hints to these Pokemon is because we as audience members KNOW that certain episodes are coming out.
But outside of league generally (which we were already told about), there's NOTHING in Pokemon Fan that suggest ANYTHING beyond the Kaki Z move episode (likely, since its Z-move related and even then that's just speculation) it doesn't even reveal Lillie will use Magearna in the Pokemon league other than information we already know about and that she obtained Magearna her father left behind.
It also doesn't expressly state what Mallow is even getting since Sophocles has a Z-ring while Mallow doesn't, but Mallow also doesn't appear to have any new Pokemon either, but she is supposed to get something in her episode with Tapu Koko and Oranguru.
So why would Pokemon Fan reveal anything beyond what we already have let alone anything in regards to Ash's Pokemon when according to the episode titles and summaries, the last Ash focused episode was his "gym battle" with Ryuki? And yet we have about 6 weeks without any mention of anything happening to Ash.
I highly doubt Meltan is Ash's ONLY power up he receives before the league (not counting new Pokemon attacks). It would be unfair to Ash if the only power up Ash gets before the league, is a Pokemon that can barely use any Pokemon attacks (and is simply strong enough to somehow participate in the league). Everyone else is getting new Pokemon as well as Z-moves. I do agree that yes Ash is MORE advantaged then his classmates, but I find it hard to believe that Meltan was Ash's last "power up" especially if we consider Gladion/Hau might have some power ups, I just don't think "Meltan" really fits here except for maybe being good against Lillie's Vulpix or potential "Ninetales" for being completely super effective against it (especially ALOLAN Ninetales).