I would say that the
Scooby Gang is fairly "organized" and that alone immediately qualifies it for use as an "Organization in Fiction". Sure, in Season 1, it had a few members, but that changed over time to grow. There are squads and their leaders, each knowing their strengths and weaknesses, etc. and eventually merging (or being affiliated, depending on someone's analysis) into the
Watcher's Council
Fictional Character Group is really saying Fictional Character "Small" Group where the small typically means under 4-5 and there is no "organizing" like my examples of "The Wonder Twins" or "Huey, Louie, Dewey"..... basically ask the question "If I saw the type "Organization in Fiction" on this fictional group, would it make me uncomfortable seeing that ?... if YES, then that's the time to use Fictional Character Group.
Perhaps "Group" name is not the best... Fictional Character Grouping ? or Fictional Character Party ? Fictional Character Cluster ? Fictional Character Pack ? Fictional Character Assemblage ?
Open for suggestions on the name. But keeping the Fictional Character part is very important.