Caribou Pirates

The Caribou Pirates are a crew who arrived at Sabaody Archipelago around the same time as the Straw Hats were reuniting. Their captains are Caribou and Coribou, which temporarily changed to Demalo Black when they joined the fake Straw Hat crew, under the belief they were real until the truth was disclosed.

History
The Caribou Pirates became famous through their two captains killing many Marines. They eventually joined the Impostor Straw Hat Pirates, but had no intention of truly following them. Instead, Caribou planned to kill them from the inside. After discovering that the crew they joined were fakes, the Caribou Pirates buried the impostors (sans Black, Cocoa, and fake Chopper, all of whom were captured) alive and then set sail, using their coated ship to follow behind the Thousand Sunny and the real Straw Hat Pirates.

Crew Strength
The crew is presumably strong, as both their captains are considered to possess the highest bounties in the new generation of rookies around the time when the Impostor Straw Hat Pirates were recruiting at the Sabaondy Archipelago. Their captain's possession of a Logia-class Devil Fruit also makes him a dangerous opponent. Having managed to make it through the first half of the Grand Line is something impressive, while dragging the remaining impostors with them. Out of Black's assembled recruits, they were the only ones to escape capture. Aside the two captains, there are at least 6 crewmembers who were resembles Coribou.

Ship
Their vessel appears to be fast, having caught up to the coated Thousand Sunny. It has only been seen as a distant silohouette under the water.

Other Information
Most of the crewmates seem to resemble Coribou, being fat with chubby faces, but with thin arms and legs. They wear dark pants, with a light unbuttoned shirt and a small dark colored top hat. Given their captain's penchant for burying his opponents alive, his subordinates (Coribou included) seem to primarily function as grave-diggers, digging graves for enemies that Caribou wishes to bury.