While Napoleon may have had an advantage in weapons and artillery, he was outnumbered by the Allied powers at the Battle of Waterloo. The French army also had terrible communication and coordination, valuable skills that cost them the battle.
Lieutenant Colonel Jongh was a Dutch military officer who wrote his account of the Battle of Waterloo about a month after it occurred, which is very valuable compared to other accounts and reports that were written months and years later. In his account, Jongh described the strategic decisions and layouts of soldiers during the battle, which showcased the unity between not only the Dutch army but also the other Allied powers. They all had a discipline about them that Napoleon's army could never compare to.
Shlomo Guil wrote a great, detailed overview of the Battle of Waterloo. In this report, he wrote that the Duke of Wellington, Arthur Wellesley, led the Anglo-Allied Army, which was composed of British, German, Belgian, and Dutch units. All these nations were willing to work together because they all wanted the same thing: to defeat Napoleon once and for all.
The Allied powers, despite their varying nationalities and opinions, all came together because of a common goal. While Napoleon was outnumbered at the Battle of Waterloo, his army simply didn't have the same level of communication that the Allied powers had. It was their unified efforts and decisions that brought an end to Napoleon's empire.