Here is a quick list of pet's that I know are catchable. I'll certainly add to this list at later dates but at the moment I have started over in another server and am not situated to start exploring.

Photo evidence can be provided if needed.

China

Red Horse- Yes.

South Island

Sheep (all four elements)-Yes
Dairy Cattle (both water and earth)-Yes
Vulture (All four elements)-Yes

Osyla

Red/Blue/Green/Yellow/Bloody/Cold/Swift/Thick Velociraptor-Yes
Red/Blue/Green/Yellow Stegosaurus-Yes
Red/Blue/Green/Yellow Triceratops- Yes
Yong Tyranosaur (all four elements)- Yes

That's all for now, but I will post more later, hopefully soon.