This has happened a few times and I have gotten past it, but now it's happening every time I make a new trainer and it's very frustrating. What happens is that when I finish making a new trainer the game the game freezes, says that it's not responding and then resets. When the resets happens it crashes because it can't read the trainer files properly. When I look at the PBS file for trainers I realise that a majority of the Trainer battles got deleted (To my knowledge nothing else gets deleted). I have no idea why this happens and it is driving me insane. PS the reason why I haven't updated is because I'm just about done with the game and I don't want to have the strain of transfering data over to be happening. Please if anyone could just help me.
If I was you, I would just edit the Trainers straight from the PBS, the Editor is bound to cause problems. I always add/edit my Trainers from the PBS notepad directly, never with the Editor.
I was going to do that, but it felt a little bit to complex and time consuming. Besides I was able to put in the trainer battles back again while I was playtesting and I've made sure to make backups because the first time it happened it deleted ALL the trainers from the new beta and I had to start all over again! XD
But either way I think I solved my problem.