>>21912639I've been wondering this too but no one here seems to know anything, so I looked around and found this:
https://www.youtube.com/watch?v=aYQv9MHoiZ0It's in spanish but if you're familiar with what he's trying to do you can follow along. Basically what you do is set the amount one of the first six items to the amount of EVs you want (256=0 EVs) and input the code for that slot. You can do this for all six stats at once.
BUT! The code seems to be borked at the moment so it doesn't actually work.
tl;dr, horde train your mons until they fix it
