All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The honor of being a Companion of the Prophet has no rival and the status of the Companion is not rivaled by the status of any person who did not attain the honor of being a Companion of the Prophet . This is an Islamic fact that is confirmed by the texts of the Quran and Sunnah (Prophetic tradition). For more benefit, please refer to Fatwa 84381.Hence, a Muslim other than the Companions will not reach their status whatever his knowledge and excellence may be.
Indeed, the scholars reported that there is a consensus that the Companions are righteous and just, and Mu’aawiyah is one of them. However, this does not mean that they are infallible as Ibn Taymiyyah said, “Ahlus-Sunnah wal Jamaa’ah do not believe that each and every Companion is infallible from committing major sins and minor sins; rather, it is possible that they would commit sins in general.”
As for describing someone who is confirmed to be a Companion to be a dissolute person, then a person who says this deserves to be punished by Allaah The Almighty because such a statement is foolishness and misguidance and daring to speak about Allaah The Almighty and His Prophet without knowledge.
Furthermore, you should know that there is a difference of opinion on whether or not Marwaan ibn Al-Hakam is a Companion; Ibn Hajar said in his book Al-Isaabah, “I do not know a scholar who is definitely sure that he (Marwaan) is a Companion.” In any case, Marwaan was one of those who had knowledge and excellence and Ibn Hajar considered him in another context as one of the greatest Taabi’is (the generation that followed the Companions), and he stated that he was among the scholars of Fiqh.
As for ‘Aa’ishah she was not killed in principle, and if you mean that Marwaan fought against her in the battle of Al-Jamal (the Camel), then the matter is totally the opposite, as he was a soldier in her army and he was the leader of the left flank of the army, as the books of history stated.
Finally, we advise the questioner not to take information about this matter from sources whose ‘Aqeedah (creed) and knowledge are not trusted, and he should beware of insulting the Companions of the Prophet because the Prophet said: “Allaah Allaah! Fear Him with regard to my Companions. Allaah Allaah! Fear Him with regard to my Companions. Do not make them the target of your attacks after me! Whoever loves them, loves them because of his love of me; whoever hates them, hates them because of his hatred of me. He who hurts them, has hurt me, and he who hurts me, has hurt Allaah, he who hurts Allaah, Allaah will punish him.” [At-Tirmithi] For more benefit, refer to Fatwa ">86382.
Allaah Knows best.