In almost every case, the pre-evolutions are better then their evolutions in this equal-BST metagame.
Yep, sight improvement in ability to take Physical attacks, but at the cost of 29 points of Special attack and 21 points of Speed. In this metagame, Pokemon can get worse as they evolve.
We just figured out why Ash's Pikachu doesn't want to evolve!
Joking aside, Eviolite looks really interesting, since a First Stage Pokemon has the same BST as a Fully evolved Pokemon, but can use Eviolite and make itself much bulkier.
...Yeah, Eviolite's gonna be banned.
Not necessarily, it wasn't banned in Little Cup, though there was some serious discussion about it, given how much it changed the metagame compared to Gen4.