You should almost always count on the Americans losing at pearl harbour. I used to be against this strategy in the original 2nd edition version as I felt the benefits did not outweigh the slower start in Asia despite the fact much of what the Japanese used in the strike could not be used elsewhere in the first round. However, in 42 I feel its important to hit first as the Japs. It does somewhat slow you down in Asia granted but its only giving the enemy some IPCs that are useful at some point in the future and may take several rounds for those IPCs to actually produce results on the ground.
Even when confronted by an all out allied blitz in the Pacific I feel it is still in Japans best interest to strike Pearl. For the most part the other targets are not a threat and can be taken care of in future rounds. I might be against the purchase of BBs and CCs but boy do I sure love to use those Japanese BBs in small naval skirmishes in the first few rounds! Japan should not feel the need to try and hit everything all at once thus splitting up her fleet up to be attacked in small pieces. Preservation of existing assests should be foremost in Japans mind.
When the Japanese go into Pearl with force the americans cannot counter attack. I like to use a third Jap fighter in the attack or the bomber, worst case scenario if the US gets 3 hits you take 1 to the BB, 1 to the sub and take 1 of the 3 air units off to keep a fully loaded CV, 1 CC and the BB. Without the US SS present a counter atack by the US is unlikely.
To challenge the Japanese fleet you need the infantry of the large fleet battle, the sub. You need at least 1 DD, trust me, you need 2 or 3. You need to be able to send 1 DD out to strike a seazone that contains more than 1 enemy SS at all times and you always need 1 DD for the fleet. You will need more than 1 CV. 1 just is not enough defense for a stack of subs against what the Japs start off with.
Bombers are great for the US but not in numbers too early. Too many bombers early means your fleet is weak on defense early. The bombers should be the last thing to build right before you plan to cause the jap fleet to retreat or fight and be destroyed. I also would not go too heavy into transports and landforces early, this slows down the build up of capital ships and thus might cost a turn or two until you achieve sufficient power to impose your will on the Jap fleet.
How should Japan defend against this? Japan attacks early and close to the US home. While there is temptation to strike again close to the US home after Pearl Harbor Japan is mindfull that the US supplies lines are short and Japans are long. The Japanese should slowly pull back so their supply lines are short and the americans are long. It buys time to clean up the chaos in the Pacific and the asian coast and lets the Japanese use their exising assests over and over again while the american firepower cannot really be used that effectively early on. But the Japanese also need land forces whereas the US does not.
By US turn 4 the US fleet should be strong enough to cause the Japs to really pull back. Modest transport and land forces combined with 4 fleet fighters and a wave of new bomber purchases should allow early island hoping. A small force of followup transports with more land forces should be built after the balance of power in naval assests have swung in favour of the US.
With all tha being said, I think the US going against Japan slows down europe too much for the benefit. A huge Japanese navy with no enemy means its next to useless after say aus and New zeland fall. With americans building forces on the west coast, flowing north then across Canada to be picked up and dropped off in europe or africa means there is no opportunity for a few jap forces in alaska or mexico to play real havoc, you already have forces there to deal with them. Sure it can threaten africa so always flow some modest forces across north africa so there are always some units to counterattack.