Pokemon that are built around moves like Earthquake, Dragon Claw, and the elemental punches should have their Attack stat maxed out. For Attack EVs, we recommend a lengthy fishing trip at Lake Valor. Using the Super Rod, you'll reel in tons of Gyarados and Seakings. Defeating them will earn you two EV points in Attack.
Above: Acuity Lakefront is an awesome place to build up a physical sweeper
For sweepers that focus on moves based on the Attack stat - like our lovely Weavile - you'll want to head to Acuity Lakefront. Here you can beat on Medichams and Sneasels for Speed EVs, as well as Snovers and Machokes for Attack EVs.
Now you know about four excellent locations for optimum EV training! Now go out and help your pokemon reach their full potential. Not only will they be stronger forces in Diamond/Pearl, a properly EV trained pokemon will give you an edge when you play against other trainers over wi-fi.