My SAT coaching institute says SAT is compulsory for NTU. But NTU's admissions team told me they will not use my SAT score. Who should I believe?

Believe what the NTU admissions team told you directly. If the people actually making admission decisions confirmed they would not use the SAT score, that is the authoritative answer. SAT coaching institutes have a financial incentive to recommend the SAT regardless of whether a specific university requires it. The mentor's experience across all Singapore university applications was that the requirements are clearly listed on each university's website, following the website and the admissions team directly is the right approach.

• For NTU specifically: based on NTU's own confirmation to this student, SAT is not required and will not be used.
• For NUS specifically: SAT is listed as compulsory for state board students on the NUS website. This is a real requirement for NUS applicants from Telangana state board and should be accounted for.
• IELTS is accepted by more universities than TOEFL and is the recommended English proficiency test. The mentor chose TOEFL only because it had a home-based version during COVID.
• An English proficiency test, either TOEFL or IELTS, is genuinely required for Singapore university applications. That part is not optional.