Why is Shell Smash even mentioned alongside Overheat on Contrary Torkoal? Shell Smash neutralizes Overheat's boosts.
Camerupt isn't really viable though.... The thing is Camerupt will have a hard time setting up with the numerous water-types like Gorebyss, Samurott, etc.
However, under Trick Room it would be a different ball game. It could use Eruption to hit hard with almost priority thanks to Trick Room.
I do not think I would be a fan of pranster haunter. First, you will be losing out on a very good ability in levitate, which even though it doesn't do much for such a frail poke, it can come in handy at times. But with prankster, would haunter invest in speed? It would have to in order to fulfill its ability in being a quick attacker, so prankster seems a little for naught. I can see a sub disable set which ensures that choiced pokes, even scarfed, cannot do anything. It would be an annoyance like liepard, but not generally difficult to defeat. A fast destiny bond would be nice, but it generally cannot take many hits to begin with to utilize destiny bond all that well. It can be a last attempt to get a kill you really need, but once destiny bond becomes a staple on haunter sets, it will somewhat easy to play around. I would probably use a shadow ball/ sludge bomb/ thunderbolt/ destiny bond set with life orb could do very well, but it already is a superb destiny bond user without prankster. So I think that prankster would be ok, but the ability to avoid earthquake and other ground moves would be annoying, and with haunter's already fast speed, I don't believe prankster haunter would make any difference.
so it's like Wonder Launcher, so to speak?