After considering that, we've decided there will be a big public zoo. All the fantastical animals like pokemon and air bisons and so on will be kept in this zoo, depowered. They won't have their memories altered and may show signs of recognizing their owners, but they'll be behind glass or bars and not able to do anything about it. (So for instance, Appa might suddenly lunge at his cage to see Aang, but that would just freak Aang out since he won't remember him.)