The USN would kill them. The Japanese would not use them properly. The Type VII dived deeper and was somewhat quieter, but if you do not know what you are doing, the characteristics that give a really marginal advantage *(such as superior sonar) means nothing in the overall scheme of things.
Probably easier kills for the RN, because the IJN boats were shallow divers, (100 meters was test depth 125 meters was crush), terrible underwater in maneuverability and noisy even by German U-boat noisy standards. They become especially vulnerable in the dive evolution, because they are very slow divers and turners (2 minutes and 7 boat lengths).
The Type 95 torpedoes were "good" out to 3,000 meters and then comes the nose wander problem caused by gyro tumble. Occasional 5,000 meter shots and hits were known and recorded, but that was the exception and not the general rule for the fish. Visibility for Japanese tracking parties through their periscopes was good even by German standards, but nobody human is going to see well at night (German attack preference time) through a periscope beyond 3,200 meters (~2 miles) in the North Atlantic day or night because of weather effects. Night surface attack in an I-15 is contra-indicated by IJN WWII tactics, so if the IJN sends instructors to teach proper stalk and underwater ambush technique, IJN style, the Germans are not going to pay any attention to their allies because they have their "own ideas" and who are these Japanese anyway?
IOW, each navy built their boats and weapon effectors to what they thought they needed and organized their tactical procedures around the mission. I-boats were there to sink Ameican battleships in attrit and decrease, and Type VIIs were there to sink British freighters in an idiotic tonnage blockade attrition strategy. Both types of subs DIED in droves, because the navies who ordered them built were functionally clueless as to how to actually employ submarines.
What made the British and Americans better, were what they tried for in their subs was; underwater dash speed, tight turn out, huge bow salvoes of fish, quieting and the best "sea worthiness" qualities surfaced or dived they could obtain in their boats. I argue that the GATOs were marginal as fleet boats as the I-15 counterpart, but they were good enough as general purpose platforms in their overall characteristics (90 meter test; 175+ meter crush, proved in battle. Those boats were massively overbuilt.) to fill fleet and commerce destroyer roles. Overall they were QUIET on the battery and hard to bracket in a turning fight against enemy escorts. Not the fastest divers (70 seconds to 70 meters) but they turned tight for their length (about 4 lengths)and UNLIKE German or Japanese boats, they did not fall out of controlled trim in radical underwater maneuvers.
Give the Germans a GATO or the Japanese for that matter, and one needs to worry. Those guys might figure out how to actually use a submarine.
en.wikipedia.org
