I say Dusclops doesn't take any damage. The card doesn't say you damage the defending pokémon, you only knock him out. Same for Misdreavus. Perish Song and Judgement don't have a base damage, and in the text it doesn't say it does damage/put damage counters, and the glossary from the rulebook only explains the TCG jargon in a general sense, and Misdreavus/Dusclops are the only 2 cards that have this effect on their attacks. So, let's look at the "attack checking", reading carefully the rulebook:
Base Damage = none
Effects applied to the base damage = none, since there is no damage
So, damage = 0 (At this exact moment, it isn't knocked out)
Attack effect= Knock out the pokémon (The attack does no damage, but the pokémon is knocked out)
If you read the rulebook, it says damage is applied before other effects, and to be knocked out isn't
exactly the same as to be damaged.
NoPoke said:
You could (if you are lucky) win a whole game using Perish Song without a single damage counter ever being placed or any damage being done.
Actually that's what one of my favourite unlimited rogue decks does, I use Misdreavus + Dark Gengar. The opponent must flip heads twice or his Pokémon goes straight to the discard pile.