Yeah, bug and fighting. Which doesn't make any fucking sense, like you said. Nearly everything else you can sorta guess type effectiveness, y'know? Plants burn, water conducts electricity, brains over brawn, so on and so forth. But with dark types it's just so damn random...

[Ah, vidya mechanics.]

But if it's not a light type then...maybe wind? We've got all the other basic elements. Flying's really the closest to that but it's not really the same thing now, is it? Especially since I've never fuckin' heard of a pure flying type.