All the cases of kukaan, except for the nominative singular, are old-fashioned. They can sometimes be used e.g. to arouse listeners' or readers' attention. In modern Finnish those cases have been replaced by the corresponding cases of kenkään — the nominative kenkään is, however, used only in poetic language, and even there very infrequently.
Several of the singular cases of "ken" can be shortened by dropping -en from the stem, e.g. kenellekään > kellekään.
Note like all Finnish personal pronouns, "kenkään" has the accusative form, kenetkään.
There are also the abessive cases, but they are very infrequently used.
There are also the instructive, temporal and causative cases, but they have by their meanings completely diverged from kukaan.