Colonel Sharp.. I can't find many details about him. I don't even know his first name. I don't beleive he was ever released as a toy, even as a Trade/Convention Special. Just going off of his animated appearance, he seems to be Army, so he's likely a West Point grad. Given his apparent age (guess 50? as of 1984?), he was also likely a mid-level officer in Vietnam and possibly an enlisted man in Korea (1934 + 18 = 1952) if he went Enlisted first as a path to getting a West Point appointment. Given his positioning as leader of G.I. Joe, he might also have known Joseph Colton and any other Black Operations 'Nam veterans that ended up in G.I. Joe personally, and may have been an Intelligence/MAC-V SOG agent in 'Nam as well, or an administrator/mission planner/strategist.
Given the regulations on officer retirement, it's highly unlikely Sharp would have been old enough for World War II, and still young enough to be a Colonel in the early 1980's and not forced into retirement or given a promotion. It seems likely that when Flagg was told to form a new Joe team around the early 1980's (1982, maybe?), he picked Sharp for his administrative skills, contacts, and personal acquaintence with at least some members of the team, which then likely formed the initial core Joe team.
Given that Sharp deliberately chose to return fire on the Dreadnoks in Revenge of Cobra, he seems to be at least an adequate combatant, certainly brave enough to at least attempt to fight them off, despite being armed only with a Laser Pistol, and calm enoguh to give deliberate, concise orders to the skiff's operator, in a clear and calm fashion. He doesn't seem prone to panic, and while he seems stiff, he certainly seems ready to give Flint and Duke the leeway they need to get the job done, indicating a respectable leader.
His appearance is similar to General Flagg in the Comics continuity, but not as "MacArthur-esque."