The villain, Zeta, was the most difficult character to animate. She boasts over 8.4 million unique hairs , 1,700 controls, and 7,000 adjustable parameters.
The character designs maintain the anthropomorphic look established in the first film, but with added personality through texture and "look development". The Angry Birds Movie 2 image
If you want to see the evolution of these designs, you can check out the official IMP Awards Poster Gallery for a look at all 18 theatrical posters. The Angry Birds Movie 2 The villain, Zeta, was the most difficult character