Mewtwo was already advertised as one of a select few Immersive Cards that Pokemon TCG Pocket players could acquire, but Mew was not really talked about at all with the method to acquire it pretty much kept secret until players figured out the unlock conditions
5 cards of rarity rare or higher, 4 uncommon cards, 5 common cards, 1 land
However it is obsoleted by Teleport, which functionally does the same thing, but gives you the chance to try moving outside your movement range whenever you want or need more movement, and in the international PlayStation version, Teleport only costs half the JP to learn while being in the Time Mage job, which is much easier to access than the Bard/Dancer jobs, which have Fly (and it's so much worse in the Japanese and PSP versions, where Fly inexplicably costs , compared to Teleport's comparatively meager 650 JP in those versions)
I just liked the way the cards looked or hoped I would get cards of players on my favorite team, the Atlanta Braves
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Magic Lost Caverns of Ixalan card list & price guide