Dear aspirant

There is no any rule and regulation are like that. Failing in MBBS is not concerned with your pg seats. Once you passed total subject of mbbs and completed training and had gotten degree then you are eligible for any colleges. You will have to clear neet pg exam or otherwise in upcoming days you will have to clear NEXT EXAM.  So don't worry about failing in mbbs almost many students fails there and grab good colleges. Your pg seats will never concerned with your failing of subject if you once passed all subjects and got your MBBS degree.

Hope it helps

To have a list of all those colleges which you can get based upon your marks, category, and state you can use NEET College Predictor:-

https://medicine.careers360.com/neet-college-predictor?icn=QnA&ici=qna_answer

Good Luck!!