OK, my five cents on how to expose weaknesses:
Germany: weak in number of troops, this should be countered by killing infantry ASAP and to outbuild the Jerries with USSR and UK especially. Counterattacks by the Russians is the way to go, especially the first three turns. Landings by UK at the Baltic coastline is a nice way to disrupt the infantry chain as well. Needless to say, threatening France and splitting reinforcements between both fronts is a game-winning strategy in mid- to late-game.
Russia: weak in IPCs and vulnerable ICs, hinder any expansion and try to take territories. This means Karelia especially where you can hinder Soviet control of Scandinavia and threaten the Archangelsk bonus. An early build of a chain of infantry towards Karelia is dangerous. Later you can take Caucasus which will cripple Russian economics, even a trade of that area can make it difficult for the Russians since they might get short on IC placement sites.
Japan: doesn’t have many weaknesses, basically logistically in the deployment of units on the mainland is the only thing. So if you can do some timely counterattacks versus Siberian, Chinese territories and India that can earn you valuable time. Retreating India’s troops to Persia and then attack back is nice, also Russian counterattacks with air support is good and one or two fighters really come in handy.
UK: navy and IPCs are both very vulnerable. We all know about knocking out the UK navy from A&A editions past and it still applies. Even more important though is to negate the Egyptian NO and grab Africa ASAP. If you take Southeast Asia and most of Africa UK will be down to 20 or so IPCs and that’s really crippling! :-P
Italy: navy is what keeps the Italians dangerous, so hitting it early is the way to go. If you can get at it before they build a CV that’s perfect, so even a suicidal attack by US or UK can be worth it if that means your ally can finish the fleet off. This means turn 2 or 3, not later! After the fleet is destroyed then Africa lies ripe for the taking, Italy’s economy is miniscule and UKs economy secure, a key to winning the game.
USA: long supply lines and a split-up front. If you can make a heavy attack at mainland USA it can easily disrupt the build-up vs. Europe and that should be a goal of Japan. Polar express not as a game-winning strategy but as a tactical move. Also when you take Midway or Hawaii they can serve as landing bases for bombers that are built in Japan and that strike at the West Coast. If you’d rather send the bombers towards Russia, you might still have made USA spent valuable IPCs on its Pacific fleet, the last laugh on you! :evil: