How is the pixel art in 2d videogames done in comparison to manga and western comics? Are they even more of a team effort? Do they trace over 3d models for animations too like some mangakas do? What are some noticeable Snes/Arcade/Genesis games where some sprites/backgrounds are just filtered photos?

Let's say, the pixel art in something like Metal Slug isn't exactly done by just 1 person, right?