I can understand putting Rimuru at 3 if we are talking about the anime but I don't even believe Rimuru was that powerful if he was using Raphael to its fullest potential and Beezlebub sure but putting Diablo lower than Luminous is insane when Luminous can't even beat Ultima before she was named and Diablo has always been way stronger than Ultima even before he was named the list frankly doesn't make any sense
