While I've not played the game this is actually based on, the first Pokémon game I ever played was Pokémon Red, on a Gameboy. (I picked Charmander, because of course I did.) Combine that with having watched really quite a lot of the original anime series, and going to see this was a foregone conclusion.
You could therefore fairly describe this as "nostalgia bait". So that's exactly what I'm going to do.
The film follows Tim Goodman (not an indicative surname, I'm sure), who receives news that his father, while investigating a case as part of Ryme City's police force, has died in a car crash. A miserable trip then, to collect his assets and begin the cinematic process of probate.
Lucky for the plot then that his father's partner, a chippy Pikachu, survived the crash, though is still suffering from amnesia caused by it. While his memory of the crash is non-existent, Pikachu is convinced that it was no accident, and is determined to get to the bottom of what actually happened, as well as work out what they were investigating in the first place. So the two of them dig through the Pokémon world to solve the mystery. There's also a bit of secondary plot which appears to take a lot from Pokémon XD: Gale of Darkness.
That's probably the most I can tell you without spoilers, so a few general thoughts before I stash all the spoilers under the usual button.
Ryan Reynolds is, as always, playing Ryan Reynolds. If you like him in everything else, you'll like him in this. I do, so I did. Justice Smith I saw in Fallen Kingdom and I think he did rather better here having been given something to do. A solid performance, if not wildly exciting.
The ensemble is also pretty damn decent, and Bill Nighy always gets full points from me for whatever he's doing, especially when that is soundin really earnest about Pokémon. It's just so silly.
Unfortunately, all of those interesting characters get stuck in a predictable plot, which doesn't taking much working out. It's too reliant on a single trick in which additional information is revealed at the end of a flashback. And then more. And then again. One reveal and a build of additional conflict would have felt more substantial than the stretching out of a plot that was a bit too thin to sustain it through the full film.
Still, the bits that were nostalgia bait worked very well on me indeed. The life given to each type of Pokémon, and how they fit into society is very clever. The Growlithe police dogs in particular were a favourite. And there's some delightful silliness with Mr. Mime. It's stuffed full of blink and you'll miss it jokes that follow naturally on from the world that's been built by the games. But it's definitely been made as a children's film. I mean, I can't be surprised by that. I enjoyed it when I was a kid, and I've brought it forward with me, rather than getting into it now. But it means that when you watch it with an older, slightly cynical eye, the gloss doesn't quite hide the gaps in the structure.
Watch it for the nostalgia, but expect to walk out of it a little disappointed.