Personally I don't understand why Dark types are weak to Bug... It doesn't make any sense to me. :x I guess Sebbaiz's reasoning does sort of make sense, but I think 'Dark' more means evil or bad rather than referring to light, doesn't it? Since half the moves are things like Thief or Beat Up... I dunno, I could be wrong or it could even be both haha. But yeah, I see no logical reason that Bug types would be strong against it. If they are referring to Dark as night/darkness then surely either Electric or Fire type attacks should be good against it too as they're able to illuminate the darkness?