Well, if someone wants to provide a zip of 100 oozes in the same GIF format as the current Petz (even if all 100 are the same - the system will still look for 100), I'll try and get it working.
The images need to be named 1.gif, 2.gif ... up to 100.gif. The system automatically adds the face, so there has to be space for that, too.
Here's an example of 1.gif for a cat. Note the image size, dimensions, and location of face space. Also note that it's a transparent gif, and the background colour shows through the "gaps" while the square itself is white.