Is it permissible to supplicate for guidance for disbelieving groups in general, or to specify a particular group (such as Jews, Christians, and secularists), and is it permissible to supplicate for a specific disbelieving individual to be guided?

It is permissible for a Muslim to supplicate for a disbeliever's guidance, and to say "Ameen" to a disbeliever's supplication for his own guidance or for victory for the believers, and so forth. It is also permissible to supplicate for a Dhimmi disbeliever for healing and good health. What is forbidden is supplicating for his forgiveness, based on the Almighty's saying: "It is not for the Prophet and those who have believed to ask forgiveness for the polytheists, even if they were relatives, after it has become clear to them that they are companions of Hellfire" [At-Tawbah:113]. However, if by supplicating for his forgiveness one intends the attainment of its cause, which is Islam, then there is no harm in that.