The selection for ME/Mtech courses is based on GATE score or rank. However, some institutes conduct Interviews or written tests for admission. They give 70% weightage to GATE scores and rest 30% is written test/ Interview.

To understand the exact procedure you should refer to the institute brochures.

Here's the link to various colleges good for ME:

https://engineering.careers360.com/colleges/list-of-me-mtech-colleges-in-india