The spider animations already have 4 different sizes in
PCP, there are also four different spider units of four different sizes. KK only added one type and size to TATW though, no clue why.
Like so;
Giant Spiders are not as powerful as Shelob or Ungoliant, but they were still large and terrible creatures. Ungoliant and Shelob had numerous spawn, and their mates included their own offspring. Throughout time they grew strong and multiplied unheeded by the Free Peoples of Middle-Earth. They now control much that is now referred to as Mirkwood. Few venture there, save for the Elves, and they do not venture far for fear of the darkness. Strengths: Variety of strong and weak units, exoskeleton armor. Weaknesses: No ranged units.
Black Spiders Chieftain (20)
Black Spiders Matriarch (40)
Black Spiders Adult (80)
Black Spiders Young (160)
Brown Spiders Chieftain (20)
Brown Spiders Matriarch (40)
Brown Spiders Adult (80)
Brown Spiders Young (160)
Forest Spiders Chieftain (20)
Forest Spiders Matriarch (40)
Forest Spiders Adult (80)
Forest Spiders Young (160)
Wolf Spiders Chieftain (20)
Wolf Spiders Matriarch (40)
Wolf Spiders Adult (80)
Wolf Spiders Young (160)
Great Eagles are done as well, 3 different sizes. KK will probably add them to TATW at a later date.
The woses shouldn't need new animations, you can use a preexisting set and scale it up a bit so they move and walk more like a caveman. Very easy to do.
This "community project" will never happen though, I couldn't even find people to help me out at all even though I was doing all the hard work.