The phrase "can't make the grade" implies that someone is incapable of meeting a certain standard or expectation. Antonyms for this phrase would highlight the opposite, indicating that someone is capable, competent or successful. Examples of such antonyms could include terms like adept, proficient, skilled, capable, talented, accomplished, successful, competent and accomplished. These antonyms would suggest that despite challenges, the individual in question is able to meet desired standards and achieve goals. So, if someone is unable to "make the grade," it's important to remember that there are plenty of antonyms that can speak to their competence, talent, and success.