Asalaamualaikum
There is no criteria for writing a verse like that in the Quran. The challenge set down by Allah is one that has no fulfilment, as Allah knew that people would try to do this and speak against the Quran, like people have done with the Torah and the Bible, as they were not protected from corruption. This challenge could in fact, be to do with the many fabricated hadiths, that clewarlty contradict the Quran, Allah knows best.........
There are however two other verses that Allah states as to the fact that the challenge to reproducing a verse like that in the Quran can not be done....even though some claim it has already been done, but they are liars.
And if ye are in doubt concerning that which We reveal unto Our slave (Muhammad), then produce a surah of the like thereof, and call your witness beside Allah if ye are truthful. ) And if ye do it not - and ye can never do it - then guard yourselves against the Fire prepared for disbelievers, whose fuel is of men and stones. 2:23-24
Say: Verily, though mankind and the jinn should assemble to produce the like of this Qur'an, they could not produce the like thereof though they were helpers one of another. 17:88
