How to apply for Andaman and Nicobar Islands Institute of Medical Science, Tomo Riba Institute Health and Medical Sciences Arunachal Pradesh and Agartala Government Medical College in state level ?
All the three institutes that you mention offer MBBS and other related PG courses. These are offered on the basis of marks scored in NEET examination conducted by NTA. So you have to write this examination and clear the cutoff marks on order to get admission.
For other details you can visit the official websites of these colleges.