Oh, cool.
I've used a lot Sharpedo in the past, and while i havent used it in bw2 i think that nothing changed for it, maybe its even stronger due to the prevalence of the rain right now. First off, sharpedo should only be used with politoed. It may sound obvious, but i saw people using it under sand or weatherless, but it just wont work, sharpedo needs all the power it can get.
The set i used was this:
Sharpedo (F) @ Life Orb
Trait: Speed Boost
EVs: 100 Atk / 252 SAtk / 156 Spd
Rash Nature (+SAtk, -SDef)
- Hydro Pump
- Ice Beam
- Crunch
- Protect
This is probably the best set in my opinion. Its special atk may seem unreliable, but it has to be noticed that its more powerfull than timid orb Starmie, and hydro pump, compared to waterfall, has 90 more base power. It also has a stronger ice move, and the fact it can hits both special and phisical walls shouldnt be underestimated. Crunch still hits enough hard even without atk investiments, koing Lati@s and sp def jellicent. The evs here are to outspeed scarftios after 2 turns, and the rest is on atk to power up crunch.
To make it work, you dont even have to support it that much. Bulky waters, keldeo in particular, Ferrothorn, are the things that can stop it more easily. there are probably some others things that i dont remember though lol
Btw, if you think about it, those things are generally a problem for any rain team, so you probably have to cover these things anyway. In my opinion, a defensive core consisting of bulky toed+the standard ferro cruel core is enough to deal with the things that stops it. Scald, toxic, and passive damage due to spikes of ferrothorn int he long run will weaken enough everything that stops it. It has to be noticed that sharpedo should only be used as a revenge killer, because it will
never have chance to switch into something, possibly in the late game when you are sure than nothing can stop you.
An antoher thing to consider, is that even bullet punch scizor koes it. breloom, dragonite, and basically every priority user can put an end to his sweep, so whatch out for them, and send it out only if these things are dead. In conclusion, sharpedo is not a bad pokemon, and if used right it can be as strong as scarfkeldeo can be in the lategame.