Lets say I use Venemoth (SW)'s Disturbance Dive attack. (Prevent all effects of an attack, excluding damage , done to Venemoth during your opponents next turn) During my opponents turn, he/she uses Banette (SW) 's Spiteful Pain attack. (If Banette is in your discard pile, this attack does 40 damage plus 40 more damage. Then, search your discard pile for Banette, show it to your opponent, and shuffle it into your deck) So if my opponent does indeed have a Banette in discard, does the added effect of 40 extra damage still apply? In other words, is the added damage an effect that is being done to Venemoth or to Banette?
It is damage, it is not an effect done to either Pokemon. It's just a calculation. So it gets done. Also, the effect of shuffling the Banette back into the deck, while an effect, is not done to Venomoth, and so is also done.