Saying its cheating? Sore loser. It would only be cheating if he said no EV training for whatever reason, and you actually agreed to it... even then, how the hell would you balance that? Its not like his Pokemon have 0 EVs. IOW, he'd probably still be a sore loser if it was random EVs. Saying its unfair because he doesn't EV train? Well, he doesn't HAVE to play with you, and you don't have to play the way he does so that he's happy, so too bad for him?
Everything in life is a battle. Even peace itself is a battle to maintain it.