How many Sailor Guardians make up the core original team in Sailor Moon, before the Outer Guardians join?

How to get close to this number

Team sizes in this genre are remarkably consistent, and that consistency is the shortcut. A core ensemble has to be small enough that every member gets distinct screen time and large enough to fill out a formation and a colour scheme — which in practice means about five. The same count recurs across decades of team-based action series for exactly that reason.

The trap is that the roster grows. A successful serialised story adds members, and someone remembering the franchise as a whole will count everyone who ever joined rather than the founding group. The question specifies the core team before the later additions precisely because the full count is a different, larger number.

The distinction between the inner and outer groups in the explanation is structural rather than cosmetic: the later arrivals belong to a different arc with a different tone, and the original five are the lineup most associated with the early seasons. Counting characters in a long-running franchise always requires deciding which point in the story you are counting at.