Is it ethical / legal for a PhD student to advertise that he is awarding PhD degrees to other students that pay him 200 USD/month?

This sounds like a straight up pyramid scheme. It may or may not be "legal" in your country but it's not a legitimate company. Run away from this.

The company that you say is offering PhD degrees to people without being an accredited university, is in India. According to India's Department of Education, regarding institutions without accreditation or an Act of Parliament:

""It is emphasized that these fake institutions have no legal entity to call themselves as University/Vishwvidyalaya and to award ‘degrees’ which are not treated as valid for academic/employment purposes."

So it is likely illegal for this company called "Bikash's Quantum" to be advertising that they can award a PhD to people that pay 200 USD/month to a PhD student named Bikash who is himself a PhD student that is basically asking for research assistants to carry out the research for his PhD.

Let me now comment on this part of the "partnership policy":

"A monthly compensation of 10000 INR or 200 USD has to be paid to BQ within the 7th day of Every English calendar month."

200 USD/month is also a lot of money in India. Many people will say that it's unethical to get people to pay you 200 USD/month do to research for you. I don't imagine this type of thing working in USA, Canada, or most of Europe, because most people are under the impression that research assistant work is either voluntary or paid, but never the other way around where the ressearch assistant pays the supervisor.

Whether or not what this guy is doing is legal in India, is something that might be a very good question to ask, and this is one place you can start.