Team TARDIS

Team TARDIS was a term used by the Thirteenth Doctor to refer to herself and her companions Graham, Ryan and Yaz. (TV: Arachnids in the UK)

The Doctor acted as the leader at most times, but on occasion had to use Graham as a proxy in places where women were not considered equals. (PROSE: The Good Doctor, TV: The Witchfinders) Regardless, she was always respected by her friends, who reinforced her rules. (TV: Arachnids in the UK, Demons of the Punjab, The Witchfinders)

Considering them to be the Guardians of History, (TV: Rosa) the Doctor made it a rule that they were to never alter events in the past when they visited. Although there were exceptions, where they needed to be part of events in order to keep time from being altered. (TV: Rosa, Demons of the Punjab, The Witchfinders, PROSE: The Good Doctor)

Team structure
The Doctor and Graham described their team as having a "very flat team structure", with each member bringing their own set of skills and areas of expertise. (TV: The Witchfinders)

The Doctor served as both the team leader (TV: Arachnids in the UK, The Witchfinders) and a teacher to her friends. (TV: Rosa, PROSE: The Secret in Vault 13)

Graham was the second oldest on the team, having years of wisdom. (TV: Rosa, Arachnids in the UK, The Tsuranga Conundrum) He was also very compassionate, defending others or trying to help them through their trauma, (PROSE: The Good Doctor, TV: Rosa, Kerblam!, It Takes You Away) even against his better judgment with someone who had hurt his family. (TV: Resolution)

Ryan served as a pupil to the Doctor, having taken her rules to heart. (TV: Arachnids in the UK, COMIC: A New Beginning, TV: The Witchfinders, The Battle of Ranskoor Av Kolos) He trusted, in the face of danger, that the group would always come out on top, (TV: The Tsuranga Conundrum) and often worked as an intermediary for the Doctor's thoughts and actions. (TV: Arachnids in the UK, The Witchfinders)

Yaz used her police officer skills in investigation and pacification to assist the Doctor in solving problems, de-escalating conflicts, and getting others to cooperate with them. (TV: The Woman Who Fell to Earth, COMIC: A New Beginning, TV: Resolution) People in need who encountered Team TARDIS were most likely to open up to Yaz, (TV: The Ghost Monument, The Witchfinders, It Takes You Away) again due to her training. (TV: It Takes You Away)