The way the Adoptables used to work was every time you loaded the main page, it showed 3 random Pokémon eggs from all the possible Pokémon to adopt. The way this has changed is similar to the way the Shelter page works. It takes a list of eggs that are already created and displays one at a time on the main page. Once you adopt the egg you want, it disappears from the main page altogether. So it's truly random, instead of just allowing you to refresh the page until you get what you want.
Eggs will be created for this new system sporadically. This kind of makes people want to come back more often, to see if the egg they're looking for is in the Adoptables.
I hope that was clear. If there's any questions, please ask them here and I'll answer!
Enjoy!
~Slix
