Can normal xbox live players ban people

You could as well ask if "normal people" can arrest other people and put them in jail.

The answer is no.

Normal people/xbox live players can report people to the police/Xbox Live Enforcement, and then there is an investigation.

If the police/Xbox Live Enforcement find that the reported person broke the law/Xbox Live Code of Conduct, the police/Xbox Live Enforcement will arrest/suspend the person that broke the rules.

So normal people can report, but not actually ban people. The banning is done by real people in the Xbox Live Enforcement team after reviewing evidence that is usually automatically sent in with the report.

So many repeat answers & they all leave out one piece of information.

The enforcement team will not accept any "evidence".They will not accept a recording your friend made same as they don't accept any videos or screenshots someone has made as these things can easily be
manipulated or tampered with.

When you report someone the enforcement team have access to all the information they need to conduct a thorough investigation.

No, he can't. You can only report a fact that violates Xbox Live conditions.

they cant 'ban' people but they can report others to the enforcement team that could lead to a ban.

The best thing to do is to report the issue and provide as much informations as your friend have. Then the case will be investigated by the Enforcement Team. Only they could ban people.