That would be too bad for Wellington — Napoleon was used up in his Russian campaign (dropped nearly 500,000 on that campaign, absolutely mind-boggling), and his former cowed allies turned on him. If that hadn’t happened, Wellington wouldn’t have been able to join battle.
Except Waterloo occurred after Nappy had already been exiled, and returned. The losses in Russia were years ago, and there were many cohorts (each annual class of men is considered a cohort) since that happened that were able to replenish the French Army. About half the Grande Armee were not French. Spanish and Portuguese soldiers were particularly prone to desertion.
Wellington had already fought the French in Spain.