can i just aimlessly train my pokemon with the EV trainer in the base and make them OVERPOWERED?
While I wouldn’t say overpowered per se, it definitely makes them stronger than they would be without any EV training at all. A mon that has EVs focused into two specific stats (or more, depending on the mon and the EV spread) is definitely stronger, whether in attacking or defenses, than a mon with random EVs. While it isn’t required to do ingame, it will only benefit you to do so.
You can reset unwanted EVs with either the EV Resetter (purchasable in your Secret Base) or the EV reducing berries purchasable in Helios’s Department Store.
Like crimson said, they aren’t nessecary but I’ve heard of a couple rom hacks that won’t let you gain EVS/have IVs so they’re nightmares lmao
crimsoncrim is 100% right and sumarised that very clearly. EV training is probably more optimal and less EV are put to waist. Ex: Sp. Attack on a Machamp because he have way less Sp. Attack than Attack (65 vs 130)
If you ever try out the Hard mode, EV training and IV breeding is necessary to keep up whit your enemys.