I think the P-39 was capable of matching the Zero below 15,000ft. Much over that an the Zero had the upper hand. I think it was used in Russia as more ground attack. I could be wrong on that. Some say the original Brewster Buffallo could dogfight with the Zero. It was slower though. Part of the problem was added weight and some poor engines in latter models. Also, as mentioned 5;1 ratios and better pilot skills, plus tactics gave the Japanese and Germans an advantage in the early years. In Russia, the russians had more planes, but they flew like drones. There were a few squadrons that flew well, the Red Guards I think. I am referencing either Gallands or Hartmanns book.
I think the Wildcat was slightly outclasses by the Zero, but it could take a licking. Suburo Sakia's account account vs Pug's Wildcat is fairly impressive. The story of both returning another day to fight is amazing. I think the Zero's main ability was its rate of climb. That let it have a higher ceiling or altitude advantage. It couldn't dive with American planes though.
Tom