I mean, we're talking about someone who could convince
Izuru, a Extraordinary Genius who's supernatural analytical and precognition skills caused him to become emotionless, to join her side and can make people commit seppuku just in a few words.
So doubt supernatural willpower or mind resistances (Since SI isn't really mind manip) would really change anything.
While it's true that most would at least resist some of her hax, Junko is so powerful due to the variety.
Law hax is useless against Immortal characters, but her Mind/Morality hax (Which affects Type 2 inorganics btw) would take care of them and vice versa.
And unlike most characters, Junko having 10^60 copies means she doesn't have to worry if one of her Monokumas get dura negged/thought based mind haxed before she can act (Which also counters most "glass cannon" type characters like Johnny and Crow)