Why he doesn't qualify[]
Yami Marik is evil and sadistic but the thing is he doesn't have moral agemcy. He is specfically stated to have been made from the darkness within Marik's heart. It was explained in great detail that he was born from Marik's hatred and pain of serving the Pharoah.
The charscters don't even really acknowledge Yami Marik as his own character but simply as "Marik" even after he gains a seoerate soul. The only other thing he is called is Marik's "darkness". There is literally zero proof to imply that he has agency. All we see from him is a sadistic charscter that does evil for it's own sake without any clear cut goals. The normal Marik wamted to strip the Pharoah of all his power because he was tired of serving him. Yami Marik wants to do it because...just because.