56mm x 87mm card sleeves Ultra Pro Board Game Lite: Standard American 56 (100) a few are even 50 microns 50 - 56 X 87mm

My wife and I have been working through the combinations and she even started a spreadsheet to track the match up favorability ranking.

Like most Pokmon cards, the value of Sabrina's Porygon depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Gym Challenge)

Japanese cards often release months before English versions and typically have lower print runs, so they often trade at higher prices than their English counterparts

The effect that returns Spirit Monsters to the hand, as well as their transparent appearance, may be a reference to them not being able to stay on the physical plane for long.

If it survives to your next turn, it retreats for free, and you start the process over again