It is likely that the Indian Navy would defeat the Pakistani Navy in the event of a conflict between the countries. The Indian military is larger and more well-equipped than that of Pakistan.
The Indian Navy has a large arsenal of nuclear attack submarines and has developed submarines that are capable of firing ballistic missiles. Pakistan would also be at a significant disadvantage as it relies on imports for about 80 percent of its petroleum and would likely run out quickly. This would be made worse by the fact that India could easily blockade many of Pakistan's major sea ports, which could quickly devastate the Pakistani economy.