Hi guys, first post on here though I’ve been reading the forum for quite some time now. I’m an international high school junior looking to apply to US universities (certainly not ivy leagues) with the top business programs. Two of my most ambitious ones are Chapel Hill at UNC, Ross Business School at UMICH and Haas at Berkeley. I’ve been told by my counsellor that all I need for a strong app is a decent IB score of around 36+ points and a decent SAT I score- I got 1380 on my first attempt. Are sat II Subject scores absolutely necessary, helpful or not at all required as my counsellor suggests? Thanks! 
NC, UMich and UC Berkeley do not require subject tests, but they consider them if submitted, and thus good subject test scores may provide help in admission. Math 2 and one in any other subject would be a good choice for business. NC actually recommends math 2 if applying for business including because it is used for placement after being admitted, and there are other schools that recommend math 2 for business so it is a good one to have if you apply for business at any college that considers subject test scores.
I believe Haas only accepts transfer students and currently enrolled Berkeley students who go through an application process after completing the prerequisites. The information is on their website.
Subject tests are not required for UCB College of Letters and Science where most Haas hopefuls start. That being said, I believe that showing additional competence in subjects that you’ve studied via SAT IIs would help an application.
UMich only consider the SAT2 score for the good of the student. It would not hurt if the score is bad. It may help your chance to get merit aid if you do have great SAT2 scores on top of great SAT1 or ACT score,