I thought with Reflect and Leech Seed or Counter, Meganium has no problem dealing with Cursers while Snorlax or Rhydon come in and set up. Bellylax should deal with Misdreavus; Raikou and Rhydon could handle non-painsplit and non-hpwater Misdreavus. Yet, it could be risky, so having Roar on Rhydon is fine.
As for other sweepers, there are many out there. The article that havoc wrote show many options. Here's another havoc's gsc article discussing about gsc offense http://www.smogon.com/forums/showthr...=attack+typing
Zapdos would be a nice addition with its electric and flying assaults taking care of water and grass pokemon respectively, as well as providing you with a Heracross counter. Bellyzard would have also been fine, but you probably don't have it. Dragonite also provides the crucial Megahorn resistance, and has the Thunder and Dynamic Punch necessary to beat down Skarmbliss. Wing Attack / Fire Blast could beat down Heracross and other grass that walls those two moves, and Double-Edge hits everything hard, including the electrics. You may want Surf or Fire Blast for the last slot to take care of Grounds such as Rhydon or Steelix, however. You could try Misdreavus, which is a bane for walls with its Mean Look and Perish Song. You could add Thunder to take care of Skarmory and Suicune that would try to Roar you out.