It needs either Fire typing or the ability Flash Fire or Magic Guard.
If it doesn't have the right immunities, it will be hard-pressed to do any punishing of any kind.
I am assuming that pokemon X is using status move when CAP9 switches in. This renders the Poison Heal and Natural Cure arguments irrelevant, since neither of them prevent the opponent using a status move on CAP9 as it switches in, nor do they get rid of the status move as long as CAP9 is in play. Shed Skin may work as an ability because it does the latter but we shall decide on that later. As long as using a status or pseudo-status move on CAP9 as it switches in for the first time actually does something to CAP9, CAP9 fails.
Acutally, what you said for Poison Heal applies only on the first turn it switches in.













