Gardevoir Lv.X and copy attacks

[KingGengar]

What if I have a Mew* d Active and powered with 2 Psychic Energy, and my opponent has a Gardy Lv.X in play, and these are the only Pokemon remaining. Gardy Lv.X has 60 hp remaining and Mew* d has 70 hp remaining. If I use Bring Down, does the attack then count that Mew* d is also Gardy Lv.X and is NOT counted in the equation regarding which is the lowest hp on the field?

Is my opponent's Gardy Lv.X protected by the attack?

If I attack in this situation, who is Knocked Out?

 

[PokePop]

"Copy" attacks are discussed in the rule book.
You would replace the text "Gardevoir" with "Mew*" in the attack.

You could use Mew* to Bring Down Gardy X.
Mew* could have 10 HP remaining and Bring Down Gardy.