To answer this question in short Yes, Parimatch is legal in India! No specific laws explicitly prohibit using online betting sites like Parimatch, apart from in the states of Telangana, Odisha and Nagaland. You can see the full list of Legal States in India below.
There are no federal laws that prohibits online betting in India. A few states have made recently explicit laws against online betting. Regulations like the Public Gambling Act of 1867 are still in place. However, there are not any cases on record of Indian players being prosecuted for online betting.