If you check the monstagram and search by rarity, you can check for yourself.
C - have them all
UC - 133 - Heimdal (I bred him once, but didnt hatch it, so doesnt appear in book)
R - 127 - Garuda M3
E - 50 - Drop Elemental (trying so hard to breed it)
L - 69 - Nemestrinus