Notice how the USER will be the pokemon that gets the lower speed.
Only three, each lowering your Speed one Stage.
When using the ability Contrary though, your Speed stat will be lowered when you use a move that boosts your Speed.
Hope This Helped :D
That's all, folks!
For an attacking move, that would be Hammer Arm and V - Create.
For a status move, that would be Curse (not used by a Ghost - Type).
Hope I helped.