Formed from various powerful crews who managed to succeed in the New World, and the representatives and some other members have been prime contestants of the Corrida Colosseum, the crew is immensely powerful indeed. In sheer numbers, they have a grand total of 5640 people from various tribes and races, being quite versatile in strength and other attributes. Five of the seven leaders were powerful enough to defeat executives of the Donquixote Pirates.
Three days later, the seven crews assisted the Straw Hat Pirates in escaping from Dressrosa and avoiding capture by the Marines. Once they reached Orlumbus' ship, the Yonta Maria, the captains of each crew asked Luffy if they could drink sake and become subordinates of his. Luffy refused, but said they would still be bonded by their fight against Doflamingo and they would help each other out at anytime. However, the captains decided to drink the sake anyway, pledging to come to Luffy's aid whenever he needed them, while Luffy was not obligated to do the same. The Straw Hat Grand Fleet was then formed, and a party ensued as their fleet departed from Dressrosa.
The fleet then separated back into their own crews. Each captain took a piece of Luffy's Vivre Card. The Tonta Corps returned to Dressrosa to help with the rebuilding operations.
Putting the combined known bounties of all of the "Straw Hats" together (both main crew and Grand Fleet) comes to a known total of 2,800,000,100 which place the grand fleet as the second highest known group bounty, behind the Big Mom Pirates.
The Grand Fleet is currently the largest known pirate group.