This animation project was a little challenging as the only asset I was able to work with was the artwork from the promo poster. Additionally, the goal was to make them look like puppets anyways, so the paper doll appearance would help.
Solution: Turning individual art from poster into puppetable paper dolls, as well as drawing frames from scratch of some body movements, mimicking the promo poster artist's painting style.
Movable parts such as heads, hands and objects were separated and placed in their own layers. During the video production process, layer manipulation and rotoscope tool in After Effects was utilized so the movable parts would sometimes be hidden and sometimes pop up smoothly during transitions.

Left: Motion graphics for objects that constantly need to be animated was utilized, as in this case it would create a smooth look and continue to emphasize a puppet cutout aesthetic rather than a frame-by-frame wheel and smoke animation. The wheels are child to the parent, which is the body of the car. This way, the wheels only rotate when the car moves and they don't need to be individually animated. The car is the only object with key frames.
The smoke from the car is entirely made up of circles and precomposed as its own animation. It has two layers to give a little depth (not too much), but it still retains the 2D appearance.