Big Blue
Cuda, I believe you are asking about qualifications to ENTER the field of mechanical engineer. If that's true, here are a few.
Have a good head for taking things apart and putting them back together
Be able to visualize complex shapes and assemblies and understand them in 3D. You can look at a drawing or diagram and totally understand what the thing does and how it works.
Be able to draw or create complex shapes and assemblies using some sort of 3D CAD program such as SolidWorks
Have a good head for math and physics. If you're not a numbers guy you'll have a hard time in mechanical engineering.
Ideally you understand machine shop operations and can figure out practical ways to design things so they can be easily made.
And finally, it helps if you have an inventive imagination.
C7S
B.S. in any engineering discipline, though a B.S. in Mechanical, Mechatronics, or Industrial Engineering is preferred.
Depending on the company, an EIT certificate and/or PE license may be needed to practice engineering for that company in that state. (U.S.A.).
The ability to work alone and solve problems without any guidance or prior knowledge of the subject.