Carl and Donut's crowd-funded faction-wars team, one of ten contesting the ninth floor.
The Princess Posse is the team Carl and Princess Donut bought their way onto the ninth floor with, entering Faction Wars as co-warlords and players rather than prey. Quasar, laying out the state of play for his niece, puts it plainly: there are now ten teams on faction wars, and the Princess Posse is one of them.
The others include the NPC team under the changeling warlord Juice Box, and the outfits belonging to the crawl's wealthy — whose personal safety protections Carl's emergency action item stripped away, meaning figures like Prince Stalwart, Operatic and Epitome Tagg are now legitimate targets.
Not described as a body of troops here; known only as a named, funded team with two co-warlords at its head.
Carl and Donut's faction in the ninth-floor war, and the vehicle by which they enter it as combatants rather than quarry.
Also appears in books you've already read — spoiler-safe to their endings: