Power Weight (HP)
Power Bracer (Attack)
Power Belt (Defense)
Power Lens (Sp. Attack)
Power Band (Sp. Defense)
Power Anklet (Speed)
Each of these items give 4 EVs in the corresponding stat, to the pokemon that holds it, even if the opponent's pokemon doesn't give off that type of EV. Example: If you battle patrat while holding the power anklet, yoor pokemon will gain 1 attack EV, and 4 Speed EVs.