Requires Imagemagick
Some scripts for resizing and processing images since I do this all the time and always forget the incantations...
To get your transparent beast go to visit this URL with your beast's ID:
https://beastopia.com/nobg/<Beast-ID>.png
like:
https://beastopia.com/nobg/0565.png
To resize a background:
tools/resize.sh assets/backgrounds/abstract-1.gif
to get this
you can edit the size settings in the resize.sh script
to composite one image over the other
x 
tools/composite.sh assets/backgrounds/abstract-1-24x24.gif assets/icons/1322.gif
to get this
These two examples are in the Makefile so you can just type:
make resize
make composite
to get an output file in assets/composite.gif