Qaisar - Arabized version of "Caesar". This title was only given to Roman/Byzantine Emperors and not to Iranian rulers.
Kisra - Arabized version of "Khosrow". Several of Sassanian kings bore the name Khosrow (I and II), and Kisra became a general word used to denote a Sassanian ruler of Iran in the context of Arabic historical writing.
Sultan - It is a later Islamic title and it was not present in pre-Islamic Iran.