Ok, this dude needs to access mysql from outside of the server.

What ports need to be open for this person to access the mysqld?

Thanks.

3306 -- and you will have to configure his account to allow access from outside localhost.

default port is 3306

Also don't forget to add his ip(s) or '%' in the dbase access list so he can access the dbase through port 3306

But need to warn you about remote dbase rises the server load a bit.