Getting ready for monster book...

Fierry is bad too, since only one of the fierrys really drops a card, you gotta double-click them before you start raping their spawn and see if that one drops a card...

same for jr boogies

No they all do. We've learned that just because you can't click an enemy doesn't necessarily mean it doesn't drop a card. It just means that specific spawn isn't the one in the book. For example, I believe Jr. Boogie 2 is the one in the book, so Jr. Boogie 1 wouldn't be clickable, but still drops a card. Iron Hook is another example of this. It's an erroneous monster and still drops the Iron Hog card.

I also believe that separated yeti and separated pepe are both capable of dropping individual monster cards for their lesser spawn. The Yeti and Pepe card appears upon the separation.