Among the professors with more than average teaching ability, list the full name and email address of the professors who advise two or more students.
more than average teaching ability refers to teachingability > AVG(teachingability); full_name of the professor = first_name, last_name; email address of the professor refers to email; advises two or more students refers to COUNT(student_id) > = 2;

SELECT T2.first_name, T2.last_name, T2.email FROM RA AS T1 INNER JOIN prof AS T2 ON T1.prof_id = T2.prof_id WHERE T2.teachingability > ( SELECT AVG(teachingability) FROM prof ) GROUP BY T2.prof_id HAVING COUNT(T1.student_id) >= 2