Is it permissible to use the phrase "may Allah be pleased with him" (radiyallahu anhu) or "peace be upon him" ('alayhi as-salam) for "Yazid ibn Mu'awiyah," and did any classical scholars praise him?

It is permissible to invoke "peace be upon him" (عليه السلام) for individuals other than prophets occasionally, but not habitually. Similarly, "may Allah be pleased with him" (رضي الله عنه) may be invoked for individuals other than the Companions, provided that the person for whom the invocation is made is among the righteous or the pious imams, and that this does not become a means of fanaticism. As for Yazid ibn Mu'awiyah, it is not permissible to invoke "may Allah be pleased with him" or "peace be upon him" for him, due to the widely known evil deeds and actions attributed to him, such as the killing of Husayn and the desecration of Medina, and due to the descriptions of his harshness and commission of abominable acts. Therefore, he does not deserve this commendation.