I actually found the earliest piece of news ever posted on Serebii.net.
This goes even further back than the September 2000 section in the Serebii news archive!
How I found it? I was having fun looking at the site through the Wayback Machine Internet Archive. I looked at the 2001 version of the site and clicked Archived News. I scrolled down to the very bottom finding the piece of news.Screen shot 2014-12-28 at 9.38.25 PM.jpg