A general management team must have expertise in each of the following areas: technical development, marketing, organizational behavior, personnel and financial responsibility. It will be rare to find a single individual with all these forms of expertise; as a consequence, the General Management team may include individuals in addition to the General Manager him/herself.
A reasonable analogy here may be made to the Release Management teams used at Autodesk and other software companies with great success. An AutoCAD release has both a manager and a chief engineer, working largely as coequals. The manager and the chief engineer are able to work effectively as a team not only because they get along well with each other, but also because there are reasonably natural lines of demarcation for deciding which partner should have final authority over each issue. Also, each manager/chief engineer pair works out the lines of demarcation in a customized way, depending on the exact set of strengths and weaknesses of the individuals.
In a similar way, General Management teams would work out lines of demarcation of the total authority that fit well with the complementary forms of expertise supplied by the team members.
Two styles of team seem natural: A General Manager accompanied by a Chief Marketing Officer, and a General Manager accompanied by a Chief Technical Officer. We may wind up with other combinations too, focusing on combinations that achieve all the objectives with a minimal number of team members.