I'm curious to know which pets are the favourite adoptions. How many are there of each type? Is my Silver Jollin uncommon among the whole of Subeta pets? Does every other person have a Scribble Fester? How many pets are there in Subeta?
I realize the numbers would change as new colours become available or people change the colour of pets in their family through the zapper or potions. Or pets are lost when people leave. I would find a rough estimate intriguing.
Sadly there isn't a tally for the color of each species. However there is a ranking of all the pet species.
While virus gave you a good place to look however do note even those numbers aren't very useful either. The numbers will forever change due to the zapper and people making general changes. Some people change their pets often, some leave them alone for ages. Also pets aren't really "lost" since the new account clear system took place. So someone can leave or be frozen and those pets still count as part of the site numbers.
You can make some broad guesses as to the popularity of pet colors by checking the prices of potions and the relative prices of elixirs vs their rarity. Marsh Arid and Scribble are not very popular. Angelic Storm and Reborn are.
During Vesnali you will be visiting user's profiles in order to beflower them. You can check out their pets that way and also give yourself a sense of the popularity of different colors that way.