- The person concerned should have:
b) Document on the basis of which the applicant has entered our country,
c) Documents certifying their 5-year stay in Greece (residence permit, etc.) and
d) Three (3) photos.
Item a) is the form they fill in at the police station with your details. Item b) is your passport. Item c) is the beige Registration Certificate. Note that there is no requirement for proof of income or proof of healthcare insurance. Although not listed, you will also be asked for proof of address which, according to the Embassy, could be a legal rental agreement, a tax statement or a utility bill. The above source is an official Greek police web site. If you are asked for proof of income and healthcare insurance you might consider drawing the officers attention to the official government guidance.
PS There is an online application form which is available in a number of languages, including English but I am not sure exactly how it works. Presumably you submit it and they phone you and tell you where and when to turn up with the documents? There is also an online form for the registration certificate if anybody is applying for the first time.
PPS This is the official Embassy guidance as a pdf