I found a site that has some higher quality pictures of all the animated characters that cameoed in the SP episode.
http://www.spscriptorium.com/Season11/E1110guests.htm
The horned Bloo looking thing in some of the pictures, is either a similar looking character from another source that I can't seem to recognize.
Or
It's Matt and Trey's rendering of Bloo, changed just enough so they don't have to face the wrath of CN's legal team.