First, France would need to have suffered some kind of "shame" as a nation.
Maybe Italy joins the CPs and America never enters the war. This caused WWI to still end in 1918, but with a CP victory. Russia falls to revolution, Britain ecsapes with a Status Quo Ante Bellum and France gets punished. They have to cede massives amounts of colonies, possibly rest of A-L, Italy's claims and harsh reparations.
Maybe this causes Germany to get lazy(Like France did) while France becomes ingenuitive(Like Germany did) and invents the blitzkrieg, uses their air force properly, ect, ect. Maybe(This is unlikely however) Germany feels bad about the treaty and becomes somewhat pacifistic(Like Britain and France were in the 30s).
They could have an Anschluss with what's left of Belgium. They could have a "Sudetland" Crisis with Switzerland.
There are three major problems with this however: Austria-Hungary and Brest-Litovsk. Maybe Austria can survive in a weakened state as a German dependency and lower tier great power(Still stronger then Italy, but below all else). Germany is going to have to somehow lose everything short of Poland and Lithuania to create any balance of power. Not sure how to get that to happen.
The third is simple; France's natural inferiority to Germany. They have half the industry(Maybe this could be eased with some prewar expansion) and little more then half the man power of Germany. They will need allies. Italy would be a potentially obvious choice, a fascist nation trying to get their claims on Austria. The other could be the Soviet Union in an unholy alliance(And in the French Hitlers mind, a temporary one), the Russians could join to regain lost land from WWI and to keep the balance of power in check.
Spain could help too I suppose. Japan could easily join them, but I'm not sure what they would bring to the table.
Britain would be in an odd postion. They can't really back Nazi's and they can't really back Germany after WWI. I'm not sure where they would go with this. Maybe they just sell weapons, food, ammuntion among other things and give loans to both sides, making a fortune off of it.
I hope some of these ideas help you.