Seaking (M) @ Life Orb 
  
Trait: Swift Swim 
EVs: 4 HP / 252 Atk / 252 Spd 
Jolly Nature (+Spd, -SAtk) 
- Megahorn 
- Poison Jab 
- Waterfall 
- Rain Dance 
  
FUCK YEAH.  Looks like I'm making a NU Rain tonight, doesn't it?  Anyways, Megahorn and Poison Jab for coverage, and c'mon it's fucking cool to use those moves as Seaking >> 
 
Waterfall cause duh.  Rain Dance cause duh. 
  
I took a speed Nature because I wanted him to be a little faster than most, however you can switch it for an Atk nature if you want.