Germany, Italy and Japan vs. USA, UK and USSR
USA, UK, and USSR were Allies. Germany, Italy and Japan were Axis enemies.
Germany and USSR
the Allied powers were Britan, France, USA, USSR, Norway, Luxemborg, Belgium, Czechslovakia, Ethiopia, Albania, Yugoslavia, Hungary, Romania, Bulgaria and Greece. Axis : Germany, Italy and Japan. Note : may include Austria.
Nobody. The war automatically ended when USA, UK and USSR defeated Germany, Italy and Japan.
China, USA and USSR
Hitler before he invaded Poland in 1939 made a pact with the USSR to give the USSR half of Poland, many people don't know that. That pact disintegrated when Hitler invaded the USSR in 1942. But his other allies were Japan and Italy. Japan was his greatest ally.
During the early part of World War Two, the distance of Japan was so far from the US that the Pacific Ocean protected Japan from invasion. The Chinese had no chance to invade Japan and the USSR had an agreement not to engage in combat until the very last days before Japan's surrender.
The Cold War involved the entire world; every country was an actual or potential enemy or friend of either the US or the USSR.
The arms race
During World War II, the USSR fought primarily against Nazi Germany and its allies, including Italy and Japan. Initially, the USSR had a non-aggression pact with Germany, but this changed when Germany invaded the Soviet Union in June 1941. The USSR was also part of the Allies, collaborating with countries like the United States and the United Kingdom to defeat the Axis powers.
American , British, & Russian Governments