Is it allowed for a single legal mangaka entity to consist of multiple artists, each of which does different part of the job, like in Bakuman? For example, one makes the stories and the other does the drawing. Will a manga publisher work with such teams?
I can't imagine why the publishers would not allow that. Historically, it has been done by many writer circles − they publish their works under one pen-name, something the readers can remember easily than the actual names of several people involved. It's a good reason to use a pen-name and publishers generally don't protest if the artist want to use one.