Many standardized tests require unique sets of skills, not just knowing curriculum content. With the right amount and type of practice, almost any student can perform satisfactorily on a standardized test, but the key words are "right amount and type." Most students are either too busy or too disinterested to put in the time.
We get asked frequently by students about which exams they should take - for example, the SAT or ACT? Does it matter? Which one is harder? Here is the best possible answer to those questions. If you are in high school, from the first moments when you have some idea which colleges you might want to apply to, call the admissions departments of those very same schools and ask to speak to someone who is knowledgeable about standardized test evaluation of student applicants. The person you will end up speaking to will work directly within, or be very closely associated with, the group that will actually be evaluating you if you apply.
The person you speak to at the college will tell you whether or not they have a preference for specific tests, and why. If there is a preference, you'll know where to spend your time practicing. If there is no preference, take some practice tests of each type and decide which one is more comfortable for you, and focus on that one. Each standarized test is designed to cover specific topics and cognitive skills; therefore there isn't one organization that governs them all.