He was the first Indian to hit 6 sixes in an innings.

Ravi Shastri is the correct answer. He hit 6 sixes in an over off Baroda's Tilak Raj in a Ranji Trophy match in 1984-85, becoming the first Indian to achieve this feat. This happened in the domestic first-class competition. While Kapil Dev was a great hitter of sixes, he did not achieve this specific record. Shastri's double-century (200*) in that innings was also notable.