Here's my Sharpedo setup, and this gives him maximum coverage from his move pool.
EV's: 252 Speed, 252 Attack, 4 HP
Ability: Speed Boost
Item: Whatever floats your goat here really.
Protect: Great for using in double battles, and sets up that first speed boost
Ice Fang: Gives coverage for; Grass, Ground, Flying and Dragon, all of which are commonly used types.
Earthquake: Great power and accuracy, Covers; Fire, Electric, Poison, Rock and Steel
Crunch: STAB, Covers Ghost and Psychic, very very commonly used type
So this bad boy hits fast, and he hits very hard. He cover's 11 of the 18 Pokemon types, so talk about useful as a sweeper :)