>>38773846I believe one of the factors is the way the franchise has been managed so far.
Despite the series having over 20 years, Pokemon as a whole is still mostly perceived as a kiddy franchise (GO notwithstanding), unlike other Nintendo properties which - for the most part- aim more towards the "all ages" crowd (the recent marketing and design choices with the newer games *cough*kids-as-MCs-and-tutorials-everywhere*cough* ain't helping shake off said stigma either).
So what happens when a "kiddie" franchise makes a movie that attemps to lure the older crowd while keeping most of the silly/bonkers stuff for the kids? You get tons confusion and indecision, which is why the movie has gathered tons of mixed opinions and shacky performance money-wise in the first place; people just don't know who's this movie aimed to (kids? pokemon fans? genwunners? everyone?).