To be fair, all this does is make it less of a penalty to lose a Pokemon you've been focused on training, and requires less time for you to be max out your level again.
It still doens't change the fact that you're going to lose to anything that has 10 more levels than your Pokemon, that's a problem with the damage formula being so level based, and how cheap it is to raise a Pokemon by 10 levels with a single night action already.