This question is already answered in the TCG rulings "important thread", but here is the compendium entry:
Q. Can Mew's "Lost Link" Poke-BODY use the attack of one half of a LEGEND Pokemon if its card is in the Lost Zone? Or what if both halves of the LEGEND Pokemon are in the Lost Zone?
A. No, you cannot. If a LEGEND Pokemon's cards are not in play, you cannot reference its attacks, Poke-POWER, Poke-BODY, etc. (HS:Triumphant FAQ; Nov 4, 2010 PUI Rules Team)
