We make a Pokemon that again can't be revenge killed or walled, but the only way it can break walls is with Explosion. No, this isn't just some gambit to make it so I get to do explosion anyway, it's the idea I stole from Korski. This is more of a wallbreaker than a pure sweeper, but it follows much of the same principle, and to balance the fact that it doesn't directly win games, we would focus on making it easier to set up. It would also have very interesting in-battle applications, being adaptable on the fly: busting holes in slower teams to end a stalemate vs sweeping more offensive teams with priority once it's BDed; sacrificing itself to take out a troublesome Skarmory, or waiting until Skarmory is gone so it can clean house? Priority and Explosion are both pretty lame without an Attack boost, so I feel we could definitely make it want to run Belly Drum, and I'm excited about the teambuilding and battling prospects of such a Pokemon.
No matter what route we take, we have to be prepared not just for revenge killers, but Pokemon with Sturdy or phazing moves. If we've ruled out late game due to competition (and I think we have) we need to focus on how CAP 6 can function well mid game once cores have been softened and proper team support is in play. Wallbreaking should be a focus.