There is no such kind of resident permit for pensioners or self-employed individuals in Greek Immigration Law. Perhaps, if I understand well, you could follow the route of the FIP residence permit option. For more details, address your case to a lawyer or a consultancy.
Non-EU citizens, without a spouse-child relationship to a Greek/EU citizen, without the possibility to acquire dual citizenship with the EU and wishing to retire in Greece or otherwise live in Greece without working, can apply for a Greek residence permit based on independent income or funds from outside the country, including retirement benefits, pensions, virtual jobs, businesses, savings or grants. It is not a work permit.
You have to issue a visa TYPE D in order to enter the country. Afterward, there is a program for financially independent persons who have a source of funds and can live without working.