Corruption of Shadows
One explanation I've gotten was that Snorlax doesn't take short breaks to relax, it takes long naps. That's the best I got.Slack Off: Snorlax. Also considering tapirs connection with sleep maybe also the Drowzee and the Munna family (at the very least the Munna family as they're whole gimmick is about dreaming. You can argue against Drowzee family as they're about putting other's to sleep but I'd think they'd be able to do it to themselves). Not sure why the Chimchar family gets it, are chimps known to be lazy? If so why are the other monkey's exclusive or am I missing something? Is it a reference to Sun Wukong?
This might have something to do with its Japanese name being Egg Lay, but then you get into the Fridge Logic of how all Pokemon lay eggs. This one can probably just be chalked down to arbitrariness.Soft-Boiled: Well the Chansey family aren't the only Pokemon with an egg, how about Exeggcute. :P Actually Togepi (and for some reason Clefairy) was able to learn it via Move Tutor in Gen III, odd but I don't think there would be a problem with Togepi getting it again.
Weezing only has 2 heads while Probopass has one (the two mini things aren't heads). Exeggcute has 5 or whatever, but Exeggutor definitely would qualify with its 3.Tri Attack: There's an entire Body Style you'd think all the Pokemon in there would be able to learn. Out of the ones who don't I'd think Exeggcute family, Weezing, and Probopass would like to have it as at least an option.
This one is weird. Its Japanese name is Wave Bullet, which doesn't explain anything unless there's some sort of Japanese culture inference like Fire Blast's specific shape. It might have to do with the concept of Chi attacks or whatnot, and technically everything that gets Focus Blast should be able to get it. This doesn't really have a good answer.Aura Sphere: Oh boy, this is a complicated on ain't it? Theoretically Lucario's signature move, even in Gen IV Togekiss and several Legendaries got it. I get the Legendaries but Togekiss? Then the Mienfoo family gets it (I suppose because its spiritual?). At least Clawitzer and Squirtle getting it makes sense because of Mega Launcher. Sticking with the Mienfoo idea you need high spiritual sense, I guess the Meditite family could learn it. Others possible candidates: Alakazam, Slowpoke family, Lugia, Ho-Oh?, Absol, Infernape? (pushing it here, but hey it can use it), Cresselia?, & Musharna (what's with me and Musharna today...). Oddly couldn't think of any Ghost- or Fairy-types, at least not in "being spiritual" sense.