Marshadow (Ghost) Unranked => S rank
A ghost type with super effective STAB against Dark and Normal types and has an amazing 125 Attack/Speed.
(I really hope it doesn't get banned because Marshadow is just what Ghost monotype needed. Finally gives them a way to deal with Dark and Normal monotypes.)
Also whether a mon gets suspected/banned or not has no relevance on how the type fares without it, but how it affects the current metagame.
Just some stuff to consider when posting for S rank specifically.