Huntail @ Life Orb/White Herb
~ EVs 252 Atk / 4 SpA / 252 Spe
~ Nature Naughty/Naive
~ Shell Smash
~ Ice Beam
Shell Smash boosts its attack Special attack and speed to nice levels, giving it a nice chance at sweeping.
Waterfall is STAB, and has pretty good neutral coverage, with a chance of flinching which one can test his or her luck with if needed.
Ice Beam hits Grass types hard, which takes Waterfalls pretty well often and also hits dragon types.
Crunch is here for bulky ghost types, who can burn Huntail after taking an attack, so this is for such occasions, and hits Psychic types harder.
Return has good neutral coverage with Waterfall.
Life Orbgive Huntail more power, but White Herb can help in setting up and helps against priority attacks as well.