Nearly all
Admiral John Tovey was the Admiral of the Fleet in the Atlantic during World War 2. He served in the Royal Navy. He retired after the war ended. Admiral Ernest J. King was assigned Fleet Commander of the Fleet for the United States once the US entered the war. They did not have one Admiral to control the fleets of the Allies as they did for the land forces.
Admiral Royal Ingersoll
There is no set number; like all fleet commands around the world, the number of naval assets assigned to 2nd Fleet changes constantly. This is because ships form different Task Forces, Battle Groups, etc., and may leave the 2nd Fleet's operational command area and enter another, or they're formed/assigned as tactical considerations warrant. Ships and other assets that might be assigned to 2nd Fleet's command may be from another Fleet; it depends on the situation and needs of the Navy.
The Atlantic
Based at Pearl Harbor.
The British stationed their fleet at Scapa Flow, in Scotland. This was so they could easily leave port and intercept any Germany attempt to get into the open Atlantic.
The Battle of the Atlantic was won by Britain and her Allies .
A smaller number of ships is a squadron. A number of squadrons make up a fleet. A large number embarked on the same mission may be called an armada.During World War II, elements of the Pacific Fleet were assigned to any of several groups called a "task force", within a larger naval operation.
Some fleet carriers (battle carriers) were used in the Atlantic, such as the USS Wasp, USS Ranger, etc. primarily to support ground landings and hunt submarines. However, the escort carriers did most of the sub hunting. As fleet carrier losses piled up in the Pacific, the USS Wasp had to be transfered to the Pacific, where she was later sunk by a Japanese submarine. The USS Ranger was considered to weak to be sent to the Pacific, and continued to work the Atlantic Theater.
WWII in Europe was decided by the movement of materiel across the Atlantic from the US to UK. Liberty ships were crucial to this venture. The predation of the UK maritime fleet by the German U boats was immense.
A group of ships is called a 'fleet', as in the English fleet fought the German fleet at the Battle of Jutland during the First World War.
The actual number changes periodically and is classified. Most numbers that you'll see in media outlets are estimates of force numbers. Actual fleet configuration and numbers is considered critical data that can be used by an enemy for attack planning, which is the reason it is not released as a definitive number to the public.