I don't quite understand why you're talking about 'curbstomping' considering the state of the respective militaries. To start from the beginning:
The North German Confederation - essentially, super-Prussia - and France are the initial likely belligerents. (Even given this, I am a little unconvinced, having recently had cause to read pieces that lead me to believe that von Bismarck was not at all as interested in war with France as one might think. But - whatever.) These belligerents are of roughly equivalent military power. Add to the North German side the states of Baden, Württemberg, and Bavaria, which have all signed mutual-defense treaties with Berlin, are part of the
Zollverein, and generally have greater ties to Berlin than to any other capital in Europe. This is the state of affairs in OTL.
If you want to widen the conflict, it is reasonable to include Austria-Hungary, which France had cause to believe would aid them in the conflict. IOTL the Habsburgs were angry with France over the 1859 war and suffering financially; both of these could conceivably have been reversed by a more vigorous French policy in providing loans to the Austro-Hungarian government to demonstrate friendship. Perhaps an exchange of military technology and advisors would not be out of the question, either. This tips the balance back over to the French side, for the NGC + south German states cannot hope to win a two-front war against opponents roughly of one and three quarters times their military power.
But keeping in mind the Convention of Alvensleben of 1863 and the OTL Russian guarantees to von Bismarck regarding Austro-Hungarian participation in any Franco-Prussian conflict, we must now add Russia to the lists in support of the North German Confederacy. Their military is easily more numerous and decidedly more powerful than that of Austria-Hungary, even though it is in the middle of Aleksandr II's reforms. Therefore the balance is once more tipped towards Berlin's side. To this we may reasonably add Italy, which is embittered at France over the issue of the Patrimony of St. Peter and over Savoy and Nice. They also are willing to fight Austria-Hungary over the Trentino and the rest of
Italia irredenta. This further tips the balance toward the North German Confederacy and Russia...but not, I think, to the level of a 'curb-stomping'. The Italian military is subpar and the Russian one is incomplete, while the Habsburgs have their own war-exhaustion, internal, and organizational problems. And France against the Germans is roughly an equal contest, barring similar luck as the French had in OTL.
Do with that information what you will.