1/ One of my favorite anecdotes of early Islamic history is when the Companion Amr. b. al-`Āṣ, who was renowned for his intelligence, eloquence and leadership skills, passed through the territory of the false prophet Musaylamāh al-Kadhāb, who insisted on meeting with him...

2/ After reciting to him some of his alleged 'revelations', Amr couldn't hide his contempt, and said to him, "I swear, you *know* that I know you're a liar!" and he stood up and left.
Those who falsely claim to be prophets need to be shown the same attitude...

3/ All that one needs to do to expose them is to narrate their 'revelations', lifestyles & teachings.
Engaging directly with the followers of the Musaylamahs of the past or present is an utter waste of time, and beneath the dignity of a true follower of the Prophet Muḥammad ﷺ.