When I last played, pet overlays weren't a site feature but a matter of html/sCode. I don't have any problem with the change, but I can't seem to find a clear answer anywhere I've looked. My pet, Bulbasaur, has both a pet and minion overlay but I haven't updated it to be hosted on subeta. My question is: do I need to do this immediately? Or can I just sacrifice the image being displayed sitewide and leave it the way it is?

Yes, you are allowed to use an overlay like you are with it only showing up on the pet's profile. The official overlay thing just makes the overlay image show up everywhere else on the site.

The main thing is that you can't be misrepresenting what the pet/minion are, which looking at the profile you're not since it still says it's a Glade Anyu and all that.

You can read more about the rules here and here.

Thank you! I didn't want to dodge any rules on accident. :p

No problem! You can submit an image to be approved as an official overlay if you want, but it's not required.