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 thought they were real until the truth was disclosed.

History
The Caribou Pirates became famous with their two captains killing so many Marines. They eventually joined the Impostor Straw Hat Pirates, but had no intention in 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 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 "super rookies". Them managing to make it through the first half of the Grand Line is also something impressive.

Other Information
Some of the crewmates seem to resemble Coribou.