Using physics constraints in mobile games can be beneficial, but it depends on the specific use case and performance requirements. For an autobattler game with a large number of characters, such as the one you described, using physics constraints on a few bones, like a character's beard, should not significantly impact performance. However, with up to 100 characters on screen, it's important to test the performance on your target devices. Physics constraints are generally not very costly performance-wise, but the overall impact will depend on the complexity of your skeletons and other processing tasks in your game. Testing with your specific setup is the best way to determine if the performance is acceptable.
