I love Klefki. He carried my team for the first ~20 matches in Super Singles Battle Maison before I met my untimely demise during an ill-timed Infernape encounter. Seriously, though, Prankster plus Thunder Wave | Substitute | Swagger | Foul Play is deliciously EVIL. Glad the cute lil' key-ring found his calling!
Same for Carbink being a Stealth Rocker/Dual Screener. Equip a Sturdy Carbink with Light Clay and you're good to go. I actually think a Klefki lead to cause frustration and spread paralysis, followed by Carbink setting up screens (and Stealth Rock, if he's lucky) for the sweepers on the team would be an interesting combo.
On a side note, since you were talking about Barbaracle, I have to say I really dig his design. He reminds me of the Pale Man from Pan's Labyrinth, if the Pale Man worked out everyday and wore a combination of striped stockings and rock armor.