I think the only bragging thread that there should be is an official, pinned "I caught a shiny ______" thread at the top of the GSC, RSE, and FRLG forums. People will be understandibly excited if they catch one, and they deserve an official thread to post about it in...though it should be enforced that the thread is not to say what shinies one has, but the shinies that one has just caught in the game corresponding to the forum it is in. Any bragging about catching rare pokemon quickly or with low-quality balls is useless.
Just my two cents.
~CK