What are some best business we can start in small tier 3 cities?

Look for a location near college, open a small cafe serving Waffle and Shakes.

Location plays major role in success of your business

Depends bro, in my hometown there is a big need for quality education and teachers for competitive exams like JEE or basic college entrance exams. Kids there have not even heard of Olympiads.

Vada pav centres / dosa shops depending on the part of the country

Definitely food business. Take a restaurant or cafe business

Massage parlors