How do I report someone that knows how to get around the report feature?

Ignore the "Xbox couldn't take action" message.It's being sent out in error.

Just report every message & leave a brief description of what the person is doing in the comment box when you report one of the messages.

You might want to block this person once you've reported them.

You would still report them through their profile or through one of the messages and leave a comment in the comment box giving more details. Ignore the message telling you they can't take action. They'll still look into it and take the appropriate action. There is a glitch that is sending that immediately after reporting someone.

It's only possible to file a complaint via the console.

For Reporting on Xbox Console you need to follow there steps in this link
support.xbox.com/.../file-player-complaint As said before make sure you only File Complaint if the Xbox LIVE player has violated any of the Xbox LIVE Code of Conduct.

It's best to create a new thread instead of bumping an old one.

Filing a complaint via the console is the only way to have the enforcement team investigate him. They investigate every complaint thoroughly. It only takes one valid complaint in order for them to take action.

If you have done nothing wrong, you have nothing to worry about if he does file a complaint on you.