Sorry, but I don't see any Soviet aircraft of 1942 comparable to Ki-84. Except for I-185 but its service was limited to combat trials during winter 1942-1943.
I think that the Italian pilots had some problems -- it was the pilots who specified the CR.42, after biplanes passed their sell-by date -- but they do seem to have been technically and tactically competent.
The Italian monoplanes were also noted for their maneuverability.
The G-50 was bit slow but both the G.50 and MC 200 were considered quite maneuverable.
They were shorter ranged than the Japanese Ki 43 and Zero but better protected in the early years and had just as good if not better armament than the Ki 43 in the early years.
Since the Italians didn't have to fly 400-600 miles most of the time it is a bit hard to see where the Japanese advantage in planes (hardware) comes from.
The British would have to employ similar tactics. Don't get into a turning fight with MC 200 or G-50.
MC 200 was stressed to a higher ultimate load than just about any other WW II monoplane and had a high dive speed, it may have take a while to get to that speed.
The Italians certainly had a number of production problems but the MC 205 was more a contemporary of the Ki 61 than the MC 202 was.
Italian aircraft being replaced by other aircraft from major countries is probably always a bit of improvement.
With that said, in a threat whose premise is 'Luftwaffe and Japanese switch aircraft', inventing the new rule ('Italians get not only Japanese aircraft, but also pilots and torpedoes') is a bit off to me.