It can take a while in an organization before people learn whether someone is really competent; especially if as you say the individual in question is particula

It can take a while in an organization before people learn whether someone is really competent; especially if as you say the individual in question is particularly good/charming at convincing others that they are effective or a necessary part of the org. If you trust your employer and management chain enough, then you can use the normal reporting loop to file concerns and notes along the way - just try not to get emotionally involved as it could become difficult to separate your observations from your personal opinions. Even more so don't let this person pressure you or change your decision-making in ways that could undermine your position. And certainly, if the organization fails to take care of things, then it may be time to move on and find somewhere more progressive and healthy. It's the sign of a failing environment if it can't identify and deal with individuals who claim overdue credit by using others' contributions.