When using movie promo Mewtwo's "Energy Absorption" attack (to
get two energy cards from the discard pile and attach to Mewtwo)
you should always pick a Double Colorless Energy as one of the
two cards, if it is available.  That way, you can use the DCE
to pay the retreat cost if necessary (should Mewtwo become
confused or poisoned, or should the opponent bring up a
psychic-resistant pokemon as active pokemon).

Here's a typical hypothetical example.  Your opponent has
fossil Magmar as active pokemon.  You make Mewtwo active,
attach a psychic energy and attack with Energy Absorption, attaching
another psychic energy and a DCE, both from the discard pile.
Then Magmar attacks with Smog and the coin flip is successful,
so Mewtwo has 30 damage and is poisoned.  On your turn
you retreat in order to end the poison, paying the 2-energy
retreat cost with the DCE, and make active a free-retreat
pokemon like Scyther, which you immediately retreat and bring
back Mewtwo, attach a psychic energy and Psyburn for 40 against
Magmar.  (In this example, if you had gotten 2 psychic energy
instead of 1 psychic and 1 DCE when you did Energy Absorption,
you would be unable to attack with Psyburn so quickly after retreating,
because Mewtwo would not have enough energy.)

Bruce Long
bruce@asu.edu