Ew, buzz kill..
Seriously, if a post is created for the sole reason of posting an unrelated gif, then that's fair enough, but when its accompanied by text relating to the topic at hand then I dont see what the problem is.. The gifs I see over in Anime Spoilers are generally used to express opinion or show feeling, which through plain text, is often difficult to do.
I don't personally post them, but they often help when someone's trying to use sarcasm or another emotion that's difficult to express on a forum. They also add a little something to the otherwise boring plain text conversation that's going on. I feel like taking that away is like taking away a persons right to express themselves on this forum and all you're doing is attempting to turn those people into robots, taking any fun that flares up and distinguishing it.. simply so you don't have to see it.
I mean, its a Pokemon forum, the majority of people coming to it are likely to be young and enjoy a bit of fun.. but you take that away? Yeesh..
For the record, I would have included an image of family guys Buzz Killington in this post if that right wasn't being taken away.