Some pointers;
1) Windows defender is a piece of junk, it's detections are often weeks behind other free AVS software.
2) What you're seeing is Windows defender taking virus detection signatures from some rather backwards antivirus companies, who consider the software used to make these trainers (CheatEngine) to be bad/evil/etc.
3) If you want a more detailed explanation, i've tried to provide one to another user here :
click me (and please excuse the vitriol in my second post there; the OP in that thread is getting on my nerves with his bullheaded insistance that he knows better than the rest of the users in the thread)
The links i provided there will show you what the trainer discussed there does when you run it, and if you check that website out further, you can see how other antivirus companies define it; you'll note some of the smarter companies simply flag it as a CheatEngine-based software, and a Possibly Unwanted Program (because, again, antivirus companies often consider trainers and such to be bad, because "hurr cheaturr!!", even if it's a trainer for a singleplayer game).
I hope this helps you understand things a bit better.
TL;DR : quite a lot of antivirus companies are retarded when it comes to trainers, and the detections are a false positive, don't worry about it too much.