Animations like that are usually made using cel shading combined with hand-painted elements. This effect is known for quite some time, occasionally it was used even in real-time rendered computer games (eg. Borderlands). Major difficulty usually comes in combining style of hand-drawn elements with 3D renders in a way where everything is consistent.
As for animation style - cel shading doesn't differ from anything else. It's just specific type of render. If you know how to correctly rig and animate character in cel shader - you know how to do it in any other render style. It's more about mastering 3D software then learning one specific animation style.