Other known variants
x2Wash Out
As often as you like during your turn (before your attack), you may move a Energy attached to 1 of your Benched Pokémon to your Active Pokémon. This power can't be used if Blastoise is affected by a Special Condition.
Hydro LauncherReturn 2 Energy attached to Blastoise to your hand. Choose 1 of your opponent's Pokémon. This attack does 100 damage to that Pokémon. (Don't apply Weakness and Resistance for Benched Pokémon.)
If Zoroark uses "Foul Play" to copy Blastoise's "Hydro Launcher" attack, do I have to be able to return 2 Water Energies to my hand in order to do the 100 damage?
No, the attack does not say "in order to" so you do as much of the attack text as you can.