Shadow Ball & Focus Punch through level up & breeding only onto Kecleon:

Sableye (Shadow Ball level up) -> Spinda -> Slakoth (Evolve to Vigroth, Focus Punch level up) -> Kecleon (and many other ground types).

Never ever have a set which *cannot* damage a whole type, unless the rest of the team has really good coverage vs that type. Any Fighting or Normal should have a way of dealing with Ghosts in particular, as they are not vulnerable to that type (in fact, Normals are immune!). Psychics have more of an excuse for not being able to deal with Dark, as they generally should not hang around against them. But a backup special attack works wonders anyway.

Another Focus Puncher I don't see mentioned as often:

Vigroth:
Yawn/Encore
Focus Punch
Shadow Ball
Return/Slash

Its stats are useable, and its special ability is excellent (can't be put to sleep). Encore is a usable alternate to Yawn to set up Shadow Punch - anything that forces a switch will do it. And as they are both level up moves you can play around with this set to suit your opponent. Shadow Ball is the only non-level up move, but it's also the only move you'd never consider removing, and at a pinch can be put on with TM.