I believe the purpose of the Bechdel test is not to identify strong women, but to identify strong characters that are female. If the only women in your story spend all their conversations chatting about the male protagonist, they are not strong characters. Alien and Terminator fail this test because Ripley and Sarah Connor are pretty shallow, one-dimensional characters even though they are strong women.

Whether you have a strong woman in your story depends on the plot. Some stories just do not have room for a strong woman. In some settings, a strong woman just does not fit. (Strong women were rarities in Victorian England and Middle Earth, for example.) But any major characters you have that are female should be strong characters. All your major characters should be strong characters, of course, but the test focuses on women because fiction has historically not been kind to the female gender.