The reason USA battleships are under represented in this game is because most were old decrepit models and were no match for the “modern” units being built by other contrys of the time.
All of the US ships were modernized in the 1930s with increased deck armor, increased gun elevations, increased AA batteries, and improved fire control. The action at Surigao Strait Strait against the Japanese Southern force of Yamashiro and Fuso was fought by 6 of the old battleships: West Virginia, Maryland, Mississippi, California, Tennessee, and Pennsylvania.
The West Virginia, Maryland, and Colorado mounted eight 16 inch guns, and were equivalent in everything but speed to the Japanese Nagato and Mutsu, with the California and Tennessee being viewed as the equals of the three 16 inch ships, but mounting twelve 14 inch guns. The Idaho, Mississippi, New Mexico, Pennsylvania, and Arizona also mounted twelve 12 inch guns. The Nevada and Oklahoma mounted ten 14 inch guns in 4 mounts, the Texas and New York mounted ten 14 inch guns in five twin mounts, and the Arkansas, the oldest active US battleship mounted twelve 12 inch guns.
The Yamashiro, Fuso, Ise, and Hyuga all mounted twelve 14 inch guns in 6 twin mounts, and saw virtually no combat in WW2 prior to the Battle of Leyte Gulf, where the Yamashiro and Fuso were sunk, and by which time the Ise and Hyuga had been converted into battleship-carriers, loosing two 14 inch mounts. The most used of the Japanese battleships, the Hiei, Kirishima, Kongo, and Haruna, were originally built as battlecruisers with eight 14 inch guns, 26-28 knot speed, but only 9 inch armor. The Hiei, as a consequence, was crippled by US heavy and light cruiser fire in the action of 13 November 1942 at Guadalcanal, taking at least 40 hits from very close range cruiser and destroyer gunfire, and then sunk the next day by US aircraft. The Kirishima was sunk on 15 November 1942 by at least nine 16 inch hits and about forty 5 inch hits from the USS Washington and South Dakota. Kongo was sunk by two submarine torpedoes in November of 1944, while the Haruna was sunk in the Inland Sea by US air attack in July of 1945. The Mutsu was destroyed by an internal ammunition explosion on June 8, 1943.
While the Texas, New York, and Arkansas were not comparable to the Japanese ships, clearly the remaining 12 US ships were at least equal to their Japanese counterparts, and superior to the Kongo=class ships in armament and armor.
The Italian ships in 1940 mounted ten 12.6 inch guns each, and had good speed but lighter armor. Cavour was knocked out of the war completely by a single torpedo hit during the British Attack on Taranto in November of 1940.
The older British ships, dating from WW1, were the Queen Elizabeth class of 5 ships, the 5 ships of the Royal Sovereign class, and the battlecruisers Hood, Renown, and Repulse. The 5 Royal Sovereigns never were rebuilt between the wars as completely as the Queen Elizabeth ships, the Renown, or the Repulse. They would be more comparable to the US Texas and New York. The Nelson and Rodney were the only post-WW1 battleships that the UK had in 1940, with the Rodney contributing in a major way to the sinking of the Bismarck.
The best single source for information on WW2 Warships is Conway’s All The World’s Fighting Ships, 1922 to 1946, and for the older WW1 ships is Conway’s All The World’s Fighting Ships, 1906 tl 1921.