If you have an Ana on your team, this gives you certain advantages such as being able to be healed from very long range, having a more offensive-favored ultimate, and having the ability to disable healing on enemies (which can be especially vital against heroes that really rely on healing such as Roadhog). That said, she also brings her own weaknesses that must be managed, such as low mobility and lower self-healing. A team may opt to run Brigitte or Lucio with Ana to help peel attackers off of her, for example.