Characters that do work
+Deadpool:
Deadpool could work in an anime well because he has swords, guns, teleporting and a healing factor. Those all fit in anime well and he has his jokes and 4th wall breaking. Deadpool works because you could make it an action/comedy anime and the level of violence in Deadpool and the interesting stories just screams "Anime-worthy"
+Ghost Rider
Imagine this for an anime; A guy who rides a flaming motorcycle, uses a chain, and can shoot fire as well as having a penance stare. Ghost rider works as an anime because he is a half-dead warrior of sorts and he has interesting villains like Blackheart and Death Ninja. Also, Ghost Rider's personal love/hate relationship with Mephisto alone could carry an anime.
+Iron Fist
Granted, We've seen this kind of anime done before. Think, a martial arts master with magic powers. Kind of makes me think of "Street Fighter". As i haven't read a huge load of Iron Fist comics, i don't know much about special villains and all but the locations and plot of some Iron Fist comics could make at least a decent anime. I mean, he ventures to another realm and befriends its people and an origin stor/training sequences for Daniel Rand could help add to the anime.
Thank you for reading