What qualifications do you need to open an immigration agency?

For example, in New Zealand, if you want to open a formal New Zealand immigration institution, you must have a formal qualification certificate issued by the New Zealand Immigration Bureau to understand the immigration regulations and conditions. Then you register a company and advertise or something.

There is another simple way. If you don't need to register with the immigration office, you can rent an office, put up some advertisements, and then transfer the customers to the formal ones mentioned above. You can charge an introduction fee.

China is usually like this. There is little formality (as opposed to informality).