Xenon Blue
No Hard Feelings
Again, it's been long established Pokemon dont need to be battle experienced killing machines to be allowed to evolve and Serena's case is such a inoffensive one in the grand scheme it's just ridiculous you're choosing this hill to die on when you have crap like Noibat which is an actual bad case of that.
I'm just using Fennekin as an example since you brought it up. Most evolution's in Pokemon is DEM because who cares about plot when you need to focus on marketing the products. I'm not saying it's terrible that Pokemon has to use DEM, I'm just saying it is in fact using DEM for most of it's evolution.