I was 13-going-on-14 when I first joined in February of 2006. I had lurked on the forums for a few months prior when I realized there was a forum past the front page, and I thought it was neat despite that forum lag--until I discovered the fan fiction section, and had a strong desire to join for that alone. It was thriving, a community within a community. There were many people I looked up to that I wanted to be like. There were fun stories just as much as there were bad stories that we can look back on and laugh.
Nowadays, the fan fiction section has basically been left to only a few active people at this point--both regular and shipping (which I think is struggling even worse). A group was talking about this this past weekend and mentioning how it looks like fan fiction on forums in general is dying out. Something about forums just aren't "adapting" or something compared to everywhere else where fan fiction could be posted. (My guess is maybe it's the new rules that were implemented a couple of years back--I know that peeved me off a bit and made me go "Lol noooope, shipping fics are more lenient than you guys". But even the shipping fic section has changed a bit, and I don't think I can blame the new mods there for it because I noticed it was going inactive before they became mods.)
For the forums as a whole, I remember it being much more active and all sorts of people were around. I also remember there being more trolls, more shitposts that (usually) gave a good chortle, just more people being silly, it looked like. It was pretty entertaining, not going to lie. Even with the drama that would pop up around the Miscellaneous section here, there was just something lively that I loved about Serebii (hoo boy, do I remember that drama. Too bad I can't talk about it here since it involves banned members). And sadly, I kind of miss that because at least it'd mean something was going on.
I thought X and Y, OmegaRuby and AlphaSapphire, or even Sun and Moon would get the forum active again, but I honestly haven't seen a big influx of people since HeartGold and SoulSilver were announced (although the new record is listed as October 11, 2013, so I guess X and Y helped? Somehow I don't remember that as much as I do with HG/SS). I have seen a bigger number of newbies sign up at the start of this year, and it did get me excited, maybe a little hopeful that the site will thrive again with some new blood, but it was too good to last, it seems. I think only a small handful of those newbies are still actively posting at this point.
I do love this site, and I'm sad to see it wane like this, but I guess that's to be expected? Serebii tries to change things up a bit, but it might be a little too late/too slow at this point? I'm not sure. Far as I know, forum activity as a whole across the web just might not be as prevalent these days like they used to be. But that's just the thing: I don't know how true that is. I just remember the Internet being a much, much different place back then when it came to these sorts of sites. Ten years is enough time for there to be noticeable changes, so another ten years should also bring about a drastic change to these forums, for better or for worse. I probably won't be here by then to tell the difference.