Battleship. It's just such a bizarre license for a movie, and certainly one nobody ever asked for. (Well, outside Hasbro execs clearly desperate for another Transformers-level hit.)
Oddly watchable in a big dumb fun kind of way, at least. And hey, it has Jesse Plemons not playing a total sociopath, so that's neat.
Perhaps, Bucky Larson: Born to Be a Star. I have a weird relationship with this movie. I know it's shit but I can't help but be fascinated by it. It's a fun movie to make your friends and family watch with you so you can watch their reaction. I wouldn't even say it's so bad it's good. It's bad but entertaining at the same time. I watch it and think "how the fuck did this get made?"
Ohh i forgot another one of my favorite. Ghost in the Shell live action. I love that movie because of Scarlett Johansson, but if you watch the original anime, everything just feels better, and the live action is simply unnecessary.
There's a distinction to point out between "absolutely no business getting made" vs "the final product turned out to be shit". I can't really think of anything that belongs to the former... I haven't actually seen most of the films mentioned here so far, except the SW sequels... which turned out to be shit, but that doesn't mean they shouldn't have made SW sequels at all: they just shouldn't have made them shit.
It seemed like a prime IP to get its time on the big screen, being that it's got a lot to build off of. But the sheer number of characters that were introduced throughout the movie and the 'all of this and more awaits,' really had me overwhelmed with having any continued interest in the "main characters" as the movie entered its third act. There were more issues, but that was the one that really sealed its fate imo.