Anime Studio uses bone animation, where you can quickly create a skeleton, which controls your 2d drawing and bends it to move with the bones. You can also drag vector graphics points around to animate deforms.
It a very different way of animating. I lends itself to certain styles, but you can animate things very quickly and easily.
Pyteo's sonic's running was animated by dragging around the bones to different positions, after creating one main sonic, and putting a skeleton on it. There may have been some dragging around of points as well, so sonic doesn't look like a total paper cutout character.
another example of anime studio animation is my contribution in this thread
the head itself is rotated on the neckbone. And all the facial expressions, and hair morphing is morphtargets for the vector curve control points. The morphtargets are nameable, so for instance the mouth animation was just two vector drawings, the neutral mouth, and the half smile. I made a 'neutral' keyframe, and a 'halfsmile' keyframe a few seconds later, and it automatically animated the in-betweens.
it used to be very annoying to use and glitchy, but smith micro eventually stepped up and updated the interface