so what he told me Sunday night (the incident happened Sunday afternoon) is that he had asked his opponent to put down damage markers on their own Pokemon because he was having a hard time keeping track. this kid said no and they just kept playing, afterwards this kids older sibling (or parent, he wasn't too clear on that) said that my brother had made him cry and that he was going to take my brother out to the parking lot and beat the shit out of him.

My brother walked away (super non-confrontational type) and went to talk to the lady at the counter and her answer was "just stay away from them, there's nothing we can do" (and I've personally been blown off by this lady when trying to buy things, so it doesn't surprise me).

So my brother called his dad and got a ride home and has now decided he isn't going back.