In delhi important institutes or exams for MBBS course are AIIMS, DU and IPUCET. There may be other colleges which I may have missed, please let me know if you need information regarding in specific college.
For AIIMS you need to appear for its own MBBA Entrance Exam. Details for the same will be available at: http://admission.aglasem.com/aiims-mbbs/
For Delhi University Entrance Exam is AIPMT but you need to fill separate Application Form. Admission procedure is yet not started. Keep visiting http://admission.aglasem.com/delhi-university-admission/ for updates.
For IPU CET you need to appear for its own MBBS Entrance Exam. Details of the same will also come later. Keep visiting http://admission.aglasem.com/ipu-cet/ for IPU related updates.
Requirements for reservation under defense quota is different for each college or university. Please wait for the application forms or notification to know exact requirements.