Even as Pokemon movies go, this one is little more than a bare faced affront to ones intelligence. Despite all of the clear positioning of this film as one harking back to the early days of Pokemon as was clearly evident in the artistic style and most obviously the plot. If you were hoping this was because the Pokemon company were trying to appeal to an older audience of fans who have been fans for years (similar to how they did for the X and Y anime) then either you are wrong for thinking that or the Pokemon company is just completely incompetent.
it didn't think my review would be like this - for the first 1/2 of the film it's actually far better than most other Pokemon films. However it quickly becomes evident that this is because it is effectively a mini anime episode and recap of prior stories as filler because the plot isn't close to being long enough for a film. The film is full of pointless filler - with team rocket appearing in the background, talking for a couple minutes then blasting off with no interaction with the characters or plot multiple times - assumedly just to fill time
Then we come to the ending. Like most Pokemon movies, this one treats the plot as an afterthought and a device for showing off the relevant legendaries (in this case Marshadow and Ho-Oh). However as it's ostensibly a kids show it's also completely essential that Ash does something Heroic in the ending and everything goes back to being fine. However in this case it just leads to the tightest knit group of Ex Machinas i've ever seen in fiction.
Again, I won't reveal too much, but suffice to say Ash vanishes without a trace in a valiant act of sacrifice. Sure would be sad if he magically reappeared out of another dimension or something - that would really make any emotional investment pointless as well as completely devaluing everything Ash gave up and sacrificed up to to that point. Oh wait, THAT'S EXACTLY WHAT HAPPENS!
That's not the only instance either, earlier in the finally Marshadow suddenly acts completely out of character for no discernible reason with absolutely no motivation whatsoever. And I won't even get started on some of Pikachu's actions towards the end - which essentially boils down to 'Fuck you, internal consistency'.
It's really disappointing because early parts are quite good and in some (what I assume are) dream sequences are wonderfully directed - especially with the fantastic use of colour in them. Those fleeting scenes though barely if at all relevant to the 'narrative' are exceptional and deserve a lot of praise.
But overall, the film is a dumpster fire because of what it is. Make no mistake - this is not a film created to be a good film, it's a film designed to show off Marshadow as an advert for the Pokemon games. It really shouldn't be seen as anything else.