The profession is divided into either psychologists or psychiatrists. You will need either a Phd or a MD to practice, depending on your philosophy and interests.
Psychiatrists are the primary caregivers in the area of mental health. They assess and treat mental illnesses through a combination of psychotherapy, psychoanalysis, hospitalization, and medication. Psychotherapy involves regular discussions with patients about their problems; the psychiatrist helps them find solutions through changes in their behavioral patterns, the exploration of their past experiences, or group and family therapy sessions. Psychoanalysis involves long-term psychotherapy and counseling for patients. In many cases, medications are administered to correct chemical imbalances that cause emotional problems. Psychiatrists also may administer electroconvulsive therapy to those of their patients who do not respond to, or who cannot take, medications.
Not all PSYCHOTHERAPY is provided by either PhD Psychologists nor by Psychiatrists. There are many licensed masters-level clinicians who perform psychotherapy.
With regard to whether one can become a licensed psychotherapist with an MBA, the answer is that licensing requirements vary state-by-state. Generally, one needs at minimum a Master's degree in mental-health, varying from Counseling Psychology, Clinical Psychology, Social Work, and so on.