Q: When a card that has a Legendary Pokemon’s attack printed on it is in the Lost Zone, can that attack be used via Mew’s “Lost Link” Poke-Body?
A: No, it can’t.
Q: When a card with a Legendary Pokemon’s attack printed on it is in the Lost Zone, can Mew use that attack via its “Lost Link” Poke-Body?
A: No, it can’t. If a Legendary Pokemon’s cards aren’t in the Active position or on the Bench, the attacks, Poke-Powers, Poke-Bodies, HP, Weakness, Resistance, and retreat cost printed on the Legendary Pokemon’s card’s pieces can’t be referenced.