I really don't like it when people go around to create fake rumors about the content of the games since it just makes them look like they want attention. Fake Pokemon can be annoying too, especially discussing if it is a fake or not, but at least fake Pokemon can be entertaining at times.
I don't care much for people complaining about how Game Freak has run out of ideas and that they should have stopped back with the first generation when they aren't familiar with the other generation. That just comes off as being blinded by nostalgia to me. People complaining about the English names for the Pokemon and characters can be really annoying too.
Avoiding spoilers and waiting for the U.S. release is really annoying and tough. I normally try to avoid reading any spoilers after the games are released in Japan regarding the storyline. I'll see the new Pokemon after Serebii posts them, but after that, I try to avoid any discussion on the video games so that the experience can feel fresh for me. It's annoying to deal with the wait, but it's worthwhile to jump into the game with little knowledge about the overall storyline.