With any PoD after February 1, 1939, can Khakhin-Gol turn into a local fight that is considered a Japanese "win"?
You can change any command decisions or personnel appointments between Feb 1939n and the time of the battle on either the Soviet or Japanese side if it helps you get the result.
Or, is this too difficult a challenge? Even with a Budyenny or Voroshilov or Kirponos in charge instead of a Zhukov, the Soviet equipment is just so much better than the Japanese and basic troop skills at handling the weapons are sufficient to beat the Japanese even if there is operational command stupidity on the Soviet side?