Did the companions of Imam Hussain who participated in the Battle of Karbala adhere to the beliefs and practices of Ahlul Sunnah?
Many of them were,previously following other than Ahlul Bayt (AS) like Zuhair Ibn Al-Qayn who was a supporter of Othman ibn Affan, but when they joined Imam Hussain (AS), they became sincere followers of Ahlul Bayt (AS) and they got the great honor of martyrdom on the live of Ahlul Bayt (AS).
Followers of Ahlul Bayt (AS) are in fact the real followers of the Sunnah of the Proohet (SAWA).
Wassalam.