Geodude MT - Choosing Benched Pokemon

[Prime]

Choose 2 of your opponent's Benched Pokemon. This attack does 10 damage to each of them. (Don't apply Weakness or Resistance for Benched Pokemon.)

If my opponent only has 1 benched pokemon, can I choose just one and do 10 damage to it, or must there be two for me to use the attack?

I ruled that the player does as much as they can. If the opponent only has one benched pokemon, then they can only choose one target to take 10 damage. The one target does not take 10 damage twice either.

Was I correct in the ruling?

 

[PokePop]

Yes, that was correct.