I'm planning on building the animated objects as a hierarchy of articulated bits. The body would be the root piece and then arms, legs etc would be attached at pivot points and animated using key frames or some basic physics for secondary movement. Something a bit like this where the pins are the pivot points.

Update : Just saw Candy Crush Saga and, coincidentally, they are using a similar style. I hate the look of that game, so I won't be going with the fastener look.