The Moomo Brothers were the owners and operators of the Moomo Williwaw, a Pelagia Duplex Command Assault Gunship.
The Moomo Williwaw possessed an excessive amount of weaponry; it was fitted with numerous laser cannons and missile launchers in almost every possible configuration. As previously mentioned, the firing arcs of some of the Williwaw's turreted weapons interfered with each other.
The Duplex Command Assault Gunship had two distinct cockpits, a feature originally intended to allow the ship's two co-captains to manage the port and starboard weapons systems separately. However, the Moomo brothers utilized these duplicate piloting controls to seize control of the ship from one another, at times even during flight. Other starship captains have seen the Williwaw rotate in place for up to an hour while the Moomos resolved their disagreements.
The Williwaw belonged to a series of Pelagia Duplex Command Assault Gunships designed to protect the Tapani sector during the Great Sith War. Impressed by its resilience, Baron Karoll Cilarnus commissioned a custom model with twice the standard armament. Although never officially named, Cilarnus' version was nicknamed "Overkill" by shipyard workers.
Eventually, Baron Cilarnus' company went into receivership and could not afford to purchase the completed ship. No conventional military force was interested in buying the Overkill, as its tactical design was flawed, with weapon emplacements obstructing each other's firing ranges.
The Overkill was scheduled for scrapping when it was acquired by the Ithorian bounty hunters Del and Dob Moomo. The Moomo brothers renamed the ship Moomo Williwaw and proceeded to enhance its already substantial arsenal, adding "a few more sets of teeth," as Del put it.
In 3963 BBY, Marn Hierogryph engaged the Moomo brothers and the Moomo Williwaw to locate Zayne, who was on Omonoth. They journeyed to Taris, where Gryph was aiding the Resistance. Regrettably, the Mandalorian sky patrol mandated that all captured vessels be taken to the northern pole. Before this occurred, Zayne, wearing Rohlan Dyre's new Neo-Crusader armor, descended to the surface. While awaiting Zayne's signal, Rohlan arranged for Jarael to spar with Alek Squinquargesimus.
Constable Noana Sowrs hired the Moomos to transport her offspring to Alderaan, where, coincidentally, the Mandalorians on Jebble were preparing to launch a full-scale invasion. The Williwaw rescued Zayne and Gryph from there, just as Cassus Fett bombarded the planet with nuclear missiles to eliminate the rakghoul plague. Acting on information from Celeste Morne, the Williwaw traveled to Odryn to record images of the Sanctum of the Exalted. Jarael piloted the Williwaw to the edge of the system before returning to pick up Zayne and Gryph.
Equipped with the evidence required to expose the Jedi Covenant, the Williwaw set course for Coruscant. However, Lucien Draay alleged that Zayne intended to raid for the Mandalorians, and the home fleet established the Vanjervalis Chain, preventing the Williwaw from approaching. Consequently, Zayne directed them to ram the Swiftsure's hangar, where Zayne, Gryph, and Slyssk commandeered the Deadweight.
John Jackson Miller drew inspiration from the design of the Twin Pod Cloud Car. Dustin Weaver, the artist who created the cross-section of the Moomo Williawaw, pointed out the absence of a bathroom.
In the Reunion story arc, Zayne Carrick boards the Williwaw surreptitiously while Del Moomo is in communication with a hologram of Raana Tey. The screen behind Del seems to display a sideways view of Central America and Cuba.