Forum Thread
Control on the EVs that a Pokémon gains
Forum-Index → Suggestions → Rejected → Control on the EVs that a Pokémon gainsIf you don't know what EVs are, please look here: Bulbapedia
The EVs are already implemented, they show up when you train with a pokemon when it says "You are training with x for a while. You concentrate especially on its Defense".
A way to control it could be it the Pokémon page, a thing that says: "What statistic do you want to train when it trains?" And opens and says "HP - Attack - Defense - Special Attack - Special Defense - Speed".
And could be an item to buy at the item shop like the "Trainer Focuser" (I'm not really good at the names and even worse if its not on my native tongue xD) where you can change the EVs that you already gained and choose its location again.
It would be a feature for battling, it would be really really useful.
Edit: to make it short, it would allow you to change quite a bit the stats of a Pokémon, it would not be so random.
edit: Found one thread while I feel there are others as well.