Hey there! :)
Hmm, this is rather interesting.
I've seen stuff like this before but have never really taken notice of it. I think that sometimes advertisements are encrypted into posts if certain keywords are written within the post.
For example, let's say I write "Water Stone" in a post. The system will find some advertisement somehow linking to a "Water Stone" and will just automatically encrypt that link under those two words within the actual post. I hope that made sense. x:
I'm not entirely sure, though, and I could be entirely wrong. This could definitely be worthy of a topic in the
PokéCommunity Questions & Feedback forum.
I'm sorry I couldn't be of much help, but I've seen this happen on other forums using vBulletin, too. I'm assuming it's the whole keyword thing.