Teachers' job responsibility has changed significantly in recent years, and now, more than ever, there are pressing needs for high quality teachers to meet the goals of education for sustainable development, especially in developing countries. This timely study examined the relationship between professional and non-professional teachers' evaluation competencies and its impact on testing complexities and student academic achievement in Nigeria. A simple questionnaire incorporating multiple statistical procedures was fashioned containing a range of questions that elicited information from 300 respondents on their perception of teachers' evaluation competencies. From the findings, it was revealed that professional teachers apply various evaluation techniques more effectively than non-professional teachers. Further, suggestions regarding measures that could help improve the employability of teachers were succinctly discussed.