The top 3 pets in each category are selected as the winners of their respective Customisation Spotlight categories. That means the pets that were voted on the most in the face-offs will rise to the top of the ranks, and the top 3 of those will be chosen! There is a little verification check from TNT before the winners are posted to make sure that everything is legitimate, but other than that, everything is chosen automatically based on the number of votes a pet receives.