Battling Pokemon which give 2 EVs instead of 1 makes training a lot easier. With Power items, getting 252 EVs becomes a simple matter of 14 full battles with the EV trainer.
With the current system, you have to do 16 full battles with the EV trainer, and then train some EV you don’t want and reset it with a berry later. It’s more complicated and time consuming than if the EV trainer just used Pokemon that gave 2 EVs
There is a Pokemon that gives 2 EVs that can be Lv. 1 for every stat.
Special Attack: Sunflora
Special Defense: Cryogonal