Very obvious
If an opponent banishes a character you've brought to the palace, their character gets banished in turn
Scryfall and other databases list legality for every card, so you can verify before buying
Check out step-by-step how-to-play videos here
Always buy graded copies from PSA, CGC, or BGS for No Rarity, CoroCoro, and Illustrator-tier cards, since raw sales at these price points carry too much authentication risk.
"The websites and scalpers make it so much less fun for everyone." We're speaking just a couple of weeks after the newest Pokemon set, Prismatic Evolutions, released in English and sold out online within hours, with thousands of fans unable to get the new cards, and web-based, bulk buying resellers sharing clips of huge stacks of Elite Trainer Boxes (ETBs), which quickly started selling on Ebay for upwards of twice the original $60 retail price