Status Update (1)
Apparently the hardest pets to get at the moment are: Scorched whelpling (seems abundant after daily resets), Arctic fox kit (requires snow weather), Silithid Hatchling (requires sandstorm weather), Minfernal (none ever spawn or extreme respawn timer), Twilight Fiendling (extreme respawn timer), Giraffe Calf (long respawn timer), Snowy Owl (requires winter), and Qiraji Guardling (requires summer).
Good Luck on your hunting everyone!
Additional Comments by Date (2)
Having both versions of this pet only counts as 1 unique ingame, but 2 on this site.