Disagree. The main motivation for serving in Congress should be just that - service to the country. Not personal power building, not a career. The actual process, writing bills, parliamentary procedure, is all managed by staff anyway. The representative or senator is mainly the face of the office and should be mostly talking with constituents and not buried in policy.
If there's one qualification test I would possibly support it would to pass a high school AP US History exam.
That's the main motivation to serving in the army, but that still requires training and exams.