Jesus Christ, how the hell is everyone 200% positive she hasn’t had Jedi training? I could easily see a scenario down the line where we discover that Rey learned from Luke and/or her family (if Luke isn’t her family) and underwent some kind of Force-induced amnesia for one reason or another. In fact, I’ll be surprised if that isn’t the case. The mind trick is really the only thing that needs explaining anyway, and possibly pulling the lightsaber. As for winning the fight, consider the following:
-Kylo Ren is himself only partially trained. Yes, he has that nifty trick where he stops blaster bolts, and yes, he’s pretty damned effective when he’s the only guy in the room with a lightsaber, but he’s not Vader and the movie never gives the impression that he’s anywhere near that level of control.
-When he fights Rey, Kylo’s just taken a bowcaster bolt to the torso and a couple decent saber hits from Finn. He’s also just murdered his father and is kind of a confused angry mess. This is not Kylo Ren on his A game.
-The movie set up quite organically through the stuff that happens on Jakku that Rey is adept at hand to hand combat and is extremely agile. Couple that with her newly awakened Force sensitivity, and I have no trouble believing she could hold her own against a Kylo Ren in the state I’ve just described.
-If that isn’t enough for you, the Force works in mysterious ways. We’ve seen it set up innumerable coincidences to drive events and shape outcomes. Who’s to say the Force itself didn’t give Rey a boost because it needed to happen? I know there’s no direct precedent for this, but have Luke or Maz expound on it in a well-written monologue in the next movie and I’ll totally buy it.
I know I’m not likely to change anyone’s mind, but when I see people take issue with stuff like this I can’t shake the feeling that it’s because they’re just unwilling to think about it. That if something in a Star Wars movie doesn’t immediately gel with the finite list of things we’ve seen in the other movies, it’s bad writing and poorly done. When I look at Rey’s arc in this movie, I don’t think “pfffft, totally unbelievable, not at all like how it was for Luke”. I think “oh shit, there’s some Force stuff going on here that we haven’t seen before, I wonder where this is going”.