When people moan about how Rey was able to take down Kylo, then i wonder if they properly watched the film. There are clues throughout and it’s all there on screen. For one , Kylo had just killed his own Father. You can see his focus wasn’t there after he did that. Then Chewie shot him with his crossbow. The same weapon that was able to blast stormtroopers and flip them through the air. He took a direct hit. Then, when he confronts them, you see how wounded he is. Against Finn, he is toying with him. But as soon as Finn manages to get a strike to injure Kylo, he quickly dispenses with Finn. Then we have Rey. Kylo has been ordered by Snoke to bring her to him. So he is hardly going to try to kill her. She isn’t exactly doing very well at first either. He pretty much has the upper hand. He has her at the edge of the newly formed cliff and then he mentions about the force. And this is when she becomes powerful against him. But wait, look back in the film and remember the speech that Maz gave her. She told her " close your eyes. Feel it. The light. It’s always been there. It will guide you". And guess what? She remembers this. closes her eyes and lets the force in to guide her. Then she is powerful enough to defeat Kylo. Even though he had had training, he was pretty injured. We also know nothing of Reys origins yet.
As if I didn’t have enough reasons to.