If we're doing ability tutors, why limit Pokemon to three abilities at all? I'm fine with saying that, for example, Whimsicott can get Prankster or Infiltrator naturally, Chlorophyll from Dream world or this ability tutor, Cute Charm from that ability tutor, and Friend Guard from that other ability tutor.
My NIDOKING brings all the boys to the yard: http://goo.gl/ExAoe
Dream world was really just... just awful, yes. And @Twilight_Sonata, allowing any pokemon to have any ability could lead to some of the most broken nonsense ever (Wonderguard Spiritomb/Sableye, Drizzle or Drought anything, etc.)
When life's really getting you down, take solace in the fact that you're going to die.