Thank you, Finno.
If you mean how many Kitaro/Medama trains, I don't really know how many they are either. I have two KF-04 (single motorized Kitaro car), the SC-01 train (Kitaro/Medama motor+trailer), and red/blue Father Eyeball motor car.
But I have seen this three car Kitaro train on YouTube:
https://www.youtube.com/watch?v=7rz-MYyx0xA
https://www.youtube.com/watch?v=aTTs8cI1hGI

Kitaro trains are JR West Japan Sakai Line
Similar is this one with the crab, fox and cuttlefish. It's not from Sakai Line, this is JR Hokkaido-East Japan train: Kiha 40 Kitsune, Kani and Ika. It's released in January 2008:
https://www.youtube.com/watch?v=mxcwtdJi51c


There are some other nice but hard-to-find KIHA 40 Plarail models (with "real" side windows, no stickers):



and this one from the Bantan Line:


There is also this blue one as a part of the set:

And this KIHA 40 rail and road set with the truck:

I really like these KIHA 40 trains!