Some of these cards are around, but this one in particular is unique for a couple of reasons
Lucario and the Mystery of Mew
Not only is it from the first edition of the Base Set, but it is also holographic and shadowless, indicating that it is from one of the first two print runs
They'll be in a special foil, "TARDIS Showcase" form, and each is uniquely numbered 500, plus the number of the given doctor
Actually, this spell returns all nonland permanents to any player's hand who played one during the turn, so if you flashed a different creature onto the battlefield before playing it, that too will be returned to your hand
Aside from those situations, though, Mewtwo EX and Gardevoir can stomp almost everything which comes at it: you can get to take advantage of Psychics massive power without the slow, plodding build-up