From the Japanese perspective there are just a few things wrong with your scenario. The IJN had been planning another "decisive battle" with the USN for more than a year; It was called the A-GO Operation and assumed that the USN would advance to attack the Marianas or The Palaus. The plan was for the Combined Fleet to sortie and, supported by Japanese naval land-based air, to attack and destroy the US Third Fleet. The bulk of Japan's surviving naval forces had been moved to TawiTawi in order to be both centrally located and also close to a source of fuel oil (Tarrakan crude from the Borneo fields).

However, in order to reinforce Biak the IJN would be forced to make a decision; the options were to proceed with the planned A-GO operation to defend the Marianas or to abandon A-GO and counter the Biak landings with a major reinforcement force. Admiral Ugaki favored the reinforcement of Biak while the Combined Fleet commander, Admiral Ozawa, felt it was far more important to preserve the IJN"s remaining power for the defense of the Marianas. He realized that the loss of the Mariana's would put the Japanese Home Islands in range of American bombers and would, in effect, foreshadow the ultimate defeat of Japan. As a typically Japanese compromise, Ozawa decided to use cruisers and destroyers, backed up by the Fuso to effect the counter landing.

In actuallity, The IJN did act immediately (within three days of the landings) to send reinforcements to Biak, however, there was no division sized ground unit available which could be moved on short notice, and, in any case, not enough transports to move a division. The only unit which was available was the Army's 2nd. Sea Duty (amphibious) Brigade, then on Mindanao in the Philippines. This was a recently formed unit with an authorized strength of about 4,000 men, comprised of three infantry battalions, a 75-mm. mountain artillery battalion of twelve guns, a tank company, and attached engineer, signal, medical, and other service-type units. The entire tank detachment, and some of the infantry and support units had been lost en route to the Philippines due to submarine attack. In the event, only about 2,500 troops were available and these had to be loaded aboard cruisers and destroyers due to lack of transports.

Another problem for the Japanese was that, far from having 200 planes with which to cover the counter landing, they had only a handful to oppose the US 13th and 5th. Air Forces which had well over 200 A-20 attack bombers alone, not to mention additional hundreds of fighters and heavy bombers. The Fifth Air Force had devastated Japanese land based air power in Western New Guinea in early 1944; for example the Japanese 23rd Air Flotilla in western New Guinea which was charged with the air defense of Biak, had only 12 fighters and 6 medium bombers. Efforts to reinforce the 23rd. Air Flotilla proved of no avail as many of the planes dispatched never arrived, and many of the piilots who did make it were immediately struck down with malaria and other tropical diseases. The Japanese launched a bombing mission of between 11 and 15 bombers; seven were shot down by shore-based AA batteries and one was downed by naval AA fire. this was the heaviest Japanese air raid against Biak. Although Allied aircraft were at a range disadvantage, their overwhelming numbers more than made up the difference.

Perhaps the worst defect the Japanese suffered was that US intelligence was reading both the IJN and IJA codes, and was well aware of Japanese intentions. The reinforcement group was repeatedly sighted and shadowed by American recon planes directed by ULTRA decrypts of Japanese operational messages. Although MacArthur's G-2 staff adamantly refused to believe the Japanese could reinforce Biak, constant shadowing of the Japanese reinforcement group kept him informed of it's progress and ultimately convinced his staff. The Japanese could not approach Biak undetected, nor surprise US naval and air forces around Biak. The first attempt at counter landings was discovered by American recon planes and called off by the Japanese. The Japanese themselves were poorly served by their own reconnaissance efforts; Japanese scout planes, at one point reported several carriers and other heavy surface units lying off Biak, causing Ozawa to delay the reinforcement unit.

The second reinforcement attempt took place a few days later and included heavy surface vessels such as Yamato ad Musashi. However, before the transport unit could approach the island, word of the American armada closing on Saipan reached Admiral Ozawa and he called off further attempts at any counter landing, ordering the fleet units near Biak to rendezvous with his carrier's in preparation for the Battle of the Philippine Sea.

If the Americans could not significantly reinforce their forces fighting for Biak, the Japanese were in an even worse situation, caught between the Biak offensive, which if successful would prevent naval operations near the Palaus and in the Philippine Sea, and the Marianas offensive which had to be stopped if Japan was to avoid strategic bombing of the Home Islands. Japan had neither enough ships, aircraft, nor oil to counter both, and was particularly deficient in aircraft and troops which could be deployed in the defense of Biak. In reality, they never had a chance to hold Biak, nor inflict a major defeat on MacArthur's forces because airpower was the key and Japanese airpower in Western New Guinea had been literally annihilated in the preceding months by the 5th. Air Force. Further, US carrier raids had destroyed much of the air power that Japan had counted on to either reinforce island bases like Biak, or defend the Marianas. The statement that "for once the Japanese actually had material superiority over the Allies" is totally inaccurate.

See this link: HyperWar: US Army in WWII: The Approach to the Philippines