Arguably, I know more about WW1 and 2 than the Napoleanic wars. I always had the impression so, tgat Napoleon came incredibly close to winning at Waterloo. Two things, mainly, sealed his defeat: one of his Generals failure to pin, defeat of aggressivle pursue Blüchers Prussian army and said armies arrival at the Battle of Waterloo. And arrival Napoleon didn't exepect due to his generals "failure" mentioned above.
I am not sure how history would have gone had Napoleon won there: France was again confined to its orld borders, Napoleons alliances across Europe were history and Spain a lot stronger. All in all, pretty much the situation he found himself in before the first coalition. Or maybe the Prussians would again have fallen in line, Great Britain exited the war. Highly unlickely so, if you ask me.