Putting Ghostceus in S rank was already mentionned by me in
November, Jibaku, Poppy, Shrang et cie already approved but for some reason, nobody edited the first post.
However, I must disagree about Steelceus being S-rank, he has a lot of check, too much imo. Also, being so dependent of the last slot doesnt help. He require too much support for this, really.
Finally, there is no way you can compare Steelceus with EKceus. Kyogre, Ghostceus and EKceus can win the game by themself, how can Steelceus be a better win conditions than someone who need ONE turn and nothing else to win the game (you're probably going to tell me that Steelceus can turn into a killing machine with just one Calm Mind, but dont forget that he got some solid check/counter and a meh STAB, which isnt the case with EKceus who can completely walk through your team if you lack toxic/a fight stab; thats the reason why he's S-rank after all).
PS : I guess I'm going to repeat myself since no mod answered but
here we go with Fightceus.