You are going to have to be a little bit more clear with your question. I don't know exactly what you are asking.
With that said, for the CFI-Airplane initial practical test, you will have to have taken the CFI Aeronautical Knowledge Test (I hope I have the current wording correctly). As far as I know, there are no substitutions, and you must take that test.
Additionally, you will need to take a Fundamentals of Instruction test, unless you already have a Ground Instructor certificate or you are an accredited teacher. Around here if one is "licensed" to teach K or 1st grade, that is considered adequate to waive the FOI test.
The knowledge for a CFI is quite different from the knowledge needed for an ATP (while ATPs may teach in their work). Furthermore, the expectations and rules for CFIs vary between countries. I know Canadian CFIs who have had to struggle with the US CFI coursework, despite their obvious competence and excellent track record in Canada.
One more item worth mentioning: The ability to answer as well as ask questions in a clear and unambiguous manner is an expectation of CFI's in the US. So you will want to hone you skills a bit, based upon the clarity of the question you asked.