You need to spend 25 minutes in a ship, 20 minutes in a plane, and 15 minutes in a sub, as well as getting 200 artillery hits, 100 AA hits, and 15 torpedo hits, kill 50 planes and 10 ships. If both people know what they are doing, this takes about 90 minutes per person. The Japanese player (JP) will get the following achievements: Medal of Honor, Bronze Star, Distinguished Service Cross, Legion of Merit, Silver Star, Torpedo Marksmanship, Artillery Marksmanship, and AA Marksmanship. The American player (AP) will get the Purple Heart. JP should build a submarine and start timing as soon as he takes control of it. Don’t leave to control or build anything else for 17 minutes (a little leeway is a good idea). Proceed to E5. AP should send ships to E5 with free fire and torpedo evade turned off and let JP sink them with torpedoes. At least 17 torpedoes should hit, and count how many ships are sunk. Sit and wait until the submarine time is up. This is a good time for AP to send the two carriers to C5. JP should then build a battleship, start timing, and go to E5 while AP builds battleships and sends them to E5 with free fire turned off. This works best if AP stops their battleships and lets JP get a full broadside from close range with 11 guns at once. It takes 3-4 rounds of this to sink an AP battleship. Count the shots fired and get to 250 in case some miss that you think hit, and make sure that at least 10 ships have been sunk at this point. JP then switches to anti-air guns and defends the battleship while AP launches 3 rounds of 18 fighters from the two carriers. Make sure they have no bombs or torpedoes, and CAP and free fire are turned off. Then take flights of fighters and fly low and level at the battleship in E5 while JP shoots down 54 fighters. At this point, you should have exceeded the 25 minutes of required ship time. JP should build a fighter and go circle for 22 minutes while AP moves the carriers next to the shipyards. JP switches back to the battleship, sinks the carriers, destroys the shipyards, game over, achievements unlocked.
Information compiled from Creech x360a's guide, found at www.x360a.org