It's really not very difficult here.
Naturalization.
That's it.
There are no other citizenship powers given to Congress.
You are incorrect. The Constitution does not limit Congress to just one type of rules. I states “Rules of Naturalization” which include those who need naturalization and those that do not need naturalization (naturally born citizen).
But enough of me citing the Constitution, historical facts and the laws of the land. Time for you to starting citing references to support your position.