Ruling Machamp Prime's "Crushing Punch" and Rescue Energy

[Ade4265]

If you had a Machamp Prime active and used the attack "Crushing Punch" to knock out the defending Pokemon that had a Rescue Energy attached to it, would Rescue Energy be discarded seperately preventing the player from using it's effect or still count as "attached to a Pokemon"?

 

[King Arceus]

You carry out effects of attacks before checking for KOs. This means Rescue Energy will be discarded so the Pokemon will not return to its owner's hand.~Mark