Back when the PokeBase was fairly new, there was a system where the site would post a little message on an answer when a question similar to the one the answer answered is asked. If you click on the link in the comment, you'll see that the question got "related to answer for ____" edited in, and no edit history, which means the site edited it in. That system was removed.
As for the retag, that must have been shown on the comment as the question it links to had been retagged.
