The largest medical entrance exam in Andhra Pradesh has been EAMCET. I suppose that if he satisfies their eligibility criteria, he should appear for EAMCET too. (Please note that the rules of AP and TS EAMCET are quite complicated. Pls read the EAMCET details and brochure at https://www.apeamcet.org/ to know the eligibility conditions).
MEDCO MCET AC
The medical and dental private colleges body conduct this exam.
Medical Entrance Exams conducted by Colleges
Don't forget that there are several All India level exams conducted by colleges separately. This includes AIIMS, JIPMER, SRM, Amrita University, COMEDK UGET and so on. There are so many MBBS entrance exams in India (please go to Medical Entrance Exams page for our aggregated list).
As the rules for Andhra Pradesh are slightly different from the rest of India, I would suggest that you scrutinize the eligibility criteria applicable for any exam before applying. But don't lose heart, there are many options available! Best of luck!