Hello, thank you for your query.
Section 323 of the Indian Pena Code punishes the act of voluntarily causing hurt. In IPC it is defined that whoever causes bodily pain, disease, or infirmity to any person is said to cause hurt. Bodily pain can also be caused by a slap on the face.
Therefore, the nature of hurt may be punishable under Section 323 of IPC may not be always of such a nature that may require a medical examination. Oral evidence of the incident may also b sufficient to prove the charge.
Therefore, while t may be advantageous to have a medical report or certificate to prove a charge under the section, it is not mandatory to have such a medical certificate for proving such charge.
Hope this helps you.