I didn't come across much romance when I was on Serebii to be honest, or I self-selected to avoid it. I'm always a bit hesitant to refer to "Pokemon Fan Fiction" as a group, though, because Serebii and Bulbagarden are really different from fanfiction.net in many fundamental ways. I tend to use fanfiction.net as the "normal" since the community is so much bigger than all the forums combined. That site is undeniably dominated by anime shipping fics. The forums tend to have fewer anime characters in general, so the romance is more between game characters or OCs. Never used Livejournal, Dreamwidth, tumblr, or deviantart so I can't comment on them.