This Golurk has an ability that makes it both Psychic and Fighting type. When it uses Superpower, and does 20 damage to itself, is the resistance from being Fighting type applied to its self-damage, making the self-damage zero damage? I wasn't 100% sure if self-damage applied Weakness and Resistance either (I couldn't find a statement in the Compendium that self-damage applied Weakness or Resistance.)
http://bulbapedia.bulbagarden.net/wiki/Golurk_(Ancient_Origins_35)
http://bulbapedia.bulbagarden.net/wiki/Golurk_(Ancient_Origins_35)