The NCAA has a sliding scale.....the lower the GPA, the higher the SAT/ACT score needs to be (and the converse....the lower the test scores, the higher the required GPA). Also, I believe there have been some recent changes to core course requirements and minimum GPA in the last year. A quick Google search can give you the sliding scale chart.
That is the minimum to play a NCAA sport in college. Colleges will have their own set of admission standards.
That being said, I know of some less-than-stellar students playing ball in college.
Additionally, once you get into college, you need to be able to stay eligible to continue to play ball in college.
You and your son, with the help of the guidance counselor if necessary, may want to do some research to target colleges that have high acceptance rates, accepts students where your son falls somewhere in the 25-75% range, or consider JUCO programs with baseball. Remember, all schools, even the Ivy's, accept students that fall "in the lower quartile".