Will a 65% in graduation be a deterrent during the placement process of a B-school like IMT, IMI, TAPMI, IIT-KGP?

A 65% in graduation shouldn’t be a deterrent during placements. Companies generally look at how you perform in your MBA. The academic percentages are only there for cut-offs and having more than 60% for that is sufficient. 

During placements, you should be able to showcase your skills and those skills should align with what the firm is looking for at that point in time. Make sure you participate in competitions as it opens up your mind and helps you gain significant knowledge on a number of different topics and perspectives. Perform above average in class when it comes to academics/cgpa, and have some achievements under your belt. That will help you stand out.