Marowak FCO 37 - Trevenant GUR 7 interaction

[Mitrox]

I have the following question:

Marowak - Ability - Bodyguard : Prevent all effects of attacks done to you or your hand by your opponent's Pokémon. Remove any existing effects.

Trevenant - Attack - Poltergeist: Your opponent reveals their hand. This attack does 30 damage for each Trainer card you find there.

Revealing the opponent's hand IS an effect. Is this prevented by Marowak's ability? If it does, how does the damage is applied? Does the opponent reveal only the Trainers quantity, but not the names and the rest of the cards? How do I make sure this is the real number? Should I play always with the judge?

Thanks!!

 

[PokePop]

From the Compendium:

http://compendium.pokegym.net/compendium-bw.html#460

Q. Does Marowak's "Bodyguard" Ability prevent me from revealing my hand from an opponent's Trevenant's "Poltergeist" attack?
A. Yes, it does. (May 18, 2017 TPCi Rules Team)

Since the hand is not revealed, no Trainers are seen.
Since no Trainers are seen, no damage is done.