As my opinion:
The US has to harass Japan as fast as possible, while Germany has its weak times, just in the first three rounds. germany usually lacks infantery on turn 2 to push their offense against the USSR.
So the US builds up a medium sized fleet in the Pacific. (including at least 2 loaded transport). Keep the fleet slightly out of range of the main japanese airforce/fleet but position to take a money island or two, remove a national objective from Japan, etc. Force them to defend a lot of places (eventually leaving one vulnerable for an attack) or force them to try to come after your fleet (1 turn the japanese fleet/airforce moves out of position) and fall back. Therefore you do not need a decesive victroy, but distract Japan from its main objectives. Maybe you have to sacrifice your pacific navy to an combined airforce and naval attack by Japan, as major distraction.
The difficult seems to be, when to turn your attention to the atlantic. If its too late then its game over.
The main point is the following:
You are forced to react on the Japanese opening round. Is Japan going straight after India, is Japan trying to take the islands first or is japan going for Russia?
UK and China should try to whittle down the japanese ground forces, while the US needs to build up some fleet, to force Japan to invest into expensive and not too useful warships.