Pokémon cards being banned from official tournament events isn't anything new - usually, a card might be deemed illegal if it turns out to be too powerful or if it affects the game in an unfair way - but this new ban is a particularly odd example.
Blaine's Quiz Show, a card from the most recent expansion on the market, Unified Minds, has been banned thanks to the potential complications it could cause when a game's two opponents speak different languages. Here's the card's text:
Put a Pokémon from your hand face down in front of you and tell your opponent the name of an attack it has. Your opponent guesses the name of that Pokémon, and then you reveal it. If your opponent guessed right, they draw 4 cards. If they guessed wrong, you draw 4 cards. Return the Pokémon to your hand.
Now, reading out the card's description and then acting upon it wouldn't usually be too difficult as translators are on hand at World Championship events; the issue actually goes a little deeper than that, as some attack names face quirky changes when translated from one language to another. French player Stéphane Ivanoff noted the issues it could cause online (thanks, PokeBeach), which appears to have resulted in the ban taking place:
"Here’s a simple situation: if I play Blaine’s Quiz Show at Worlds, using a French Pokémon card, should I announce the name of the attack in French or in English?
-> If it’s in French: unless my opponent speaks French, they probably can’t guess the Pokémon. Is this an intended effect of the card?
-> If it’s in English: What if I don’t know the English name of the attack (since my card is in French)? Also, even if I know the name, what if my opponent doesn’t speak English (say it’s a Japanese player)?
"If using translators, there is one major issue: attack names don’t always map one-to-one between languages. Here is an example:
Lillipup (BLW 81) and Gliscor (UNB 99) have the same attack Collect. In French, Lillipup’s Collect was translated to 'Collectionner,' and Gliscor’s Collect was translated to 'Collecte.'
If I play against a French-speaking player and announce “Collectionner,” they know it can be Lillipup and not Herdier. If I play against an English-speaking player and announce “Collect,” it can be both. This means that doing the exact same game action has different results depending on the language used."
Thanks to the nature of the issue, the card has reportedly been banned from Worlds events only - events unaffected by language barriers are still good to go. Having said that, it would be quite a surprise to see someone using the card in an official tournament anyway - it seems pretty risky to us!