This movie (and of course its trailer) seems to target its audience very precisely, maybe you're not that target.
For example,
the music at 8 seconds in the trailer is from
the main menu theme in the first Pokémon games.
So the people who are into Pokémon but are too young to be nostalgic of this because they started with Pokémon White are missing something.
Same, the people who are into Pokémon but are a bit too old to think "haha yeah me too, so true, the feels" when they hear "you wanted to be a Pokémon trainer when you were young // yeah... that didn't really work out" are missing something.
And of course the people who are not even into Pokémon are not the target at all.
This movie is really for these people in their twenties who played the first games, and still know some of the new Pokémon such as Greninja, and wanted to be Pokémon trainer, and wanted Pokémon in the real world exactly how they are pictured in this movie (not an anime).
Exactly the category of persons that was the most into Pokémon Go when it was out at the beginning, and then they stopped playing it because it was not exactly what they expected (fights? exchanges?) (which does not mean everyone stopped playing it), so yeah, maybe then the scenario will be shit, I don't know, but really the trailer is only meant to be fully appealing to this category of persons.