That is scary

But it does sound like a fun way to play mindgames with your oponent
No, it removes the mindgames altogether because the opponent can see not just every card in your hand (which doesn't guarantee a win), but if reports are to be believed, once you pick a move they can see it before picking theirs. Say they throw out a Wobbuffet: the Battle Analyzer gives them
perfect certainty about whether you're going to use a physical or special move and, thus, whether they should Counter or Mirror Coat it. So unless you have a recovery move, Ghost-type physical striker, Dark-type special striker, or can somehow win through status ailments, they are
going to win every time.
I hope Gamefreak patches again. D:
I don't want this thing around.
Unpatchable, sorry. Not for being
technically impossible to fix (all the game has to do is transmit a 'ready' code to the other player, and after all players are 'ready' THEN it transmits the details about each chosen actions), but because the patch would have to be server-enforced mandatory (like the MK7 online patch) for all players, because the patched version would be non-compatible with unpatched version.
Reportedly the Pokecheck guys are being more white hat about the subject and are even working on an (unofficial, of course) app that can counter it. In the meantime, the only guaranteed way to prevent your opponent from being told in advance of your move (if you suspect they're using the Battle Analyzer) is to run out the clock. Which would make battles REALLY long and drawn out . . .
possibly the perfect torture for those cheaters.
I don't know of any Nintendo game that patched itself to protect against hacks. This thing's gonna stick around and redefine the game for the entire generation.
It really only affects Internet play. Since the Battle Analyzer is a separate app that relies on setting up your own network to sniff packets with, it's NOT going to affect local (in-person) multiplayer or official tournaments.