Machika is entirely normal human without mental barriers and silly things like that. She does, however, have lots of immortals who might want to stab/maim/kill Charles if he does anything skeevy with his mental powers. Otherwise it's all good! A general note is that she thinks about Rain a lot, and her various friends.

Leo has some kind of mental blocks! Canon has not specified what they are, but when someone tries to control his mind and body it basically does not work. His memories are also pretty blocked, probably? I am just going to say they are for now because I can't figure out canon. But basic mind-reading and talking to him in his mind still works just fine. Thinks about Elliot a lot...mostly about how much trouble he is.

Kurt/Nightcrawler knows a Professor X in his world! Said Professor is old and bald and like the Grandfather of the Institute. Kurt does not think he is perfect, but he respects his Professor greatly and holds him in very high esteem! Also the Professor is the one responsible for making his holowatch so that he can appear human. Because the Professor likes talking in their heads and poking around a lot, Kurt can kind of pick up on if his mind is being invaded. But if Charles is being subtle then it's unlikely that he will notice! Otherwise everything else is fair game. Although there will be So Much Judging of the young Professor X and his morally ambiguous ways. Also he's probably thinking about food all the time.