TBSF Makes All Their Sonic the Hedgehog Blender Rigs Free Forever
This includes 7 rigs you can play around with.
TBSF made all of their Sonic the Hedgehog Blender character rigs free forever. Those include Shadow the Hedgehog, Amy Rose, Tails the Fox, and 4 different Sonic rigs. They are animation-ready and have support for both inverse and forward kinematics, as well as proper squash and stretch thanks to deformation-friendly lattices and bendy bones.
Shadow the Hedgehog is the latest addition to the collection. It's already available as an early release, but the final version will be out on October 1. Unlike the rest of the Sonic rigs, this one was created with the RigUI add-on in mind, so TBSF recommends getting it before tweaking the model. Plus, the artist is constantly updating and improving their previous rigs.
TBSF runs a Discord server where you can ask questions if something seems off, and another Blender artist or TBSF themselves will help you out. The artist warns that all their rigs are made for intermediate Blender users and are not beginner-friendly. They have all the sculpting, shading, and movement handled, but scene setup, lighting, and rendering are still on you.