Serebii (or any other admin), can you reconsider your stance on including recently announced content in the site-wide banner?
Serebii.net is a fantastic resource for fans, but with the inclusion of the Kanto Starters in the banner, I can't recommend people come here any longer. Bulbapedia is a dangerous resource as well. For example, their Blaziken page just jumps right out with Mega Blaziken.
People have been able to avoid spoilers by just navigating to a part of your site that wasn't index2.shtml, such as serebii.net/pokedex-bw/ and being perfectly content in avoiding spoilers.
Yes, some people would like to go into these games as blind as possible. One person on reddit had mentioned how he got exposed to spoilers because of the recent addition of an auto-forwarding script on serebii.net/ which brought you straight to serebii.net/index2.shtml They had in the past been using the footer links to navigate the site.
If you'd place the banners with new content only on the index2.shtml page, I think that'd be a great compromise.