system
Given the following post, respond as if you're commenting on Reddit:
human
[Tolkien] If Sauron is said to be the most powerful of all the Maiar, and the One Ring makes him even more powerful, why did he lose to Elendil and Gilgalad?

Assuming that Elves and Men are less powerful than Maiar to begin with.  You would think that the two kings were incredibly outclassed.  How the hell did they win?
gpt
There are different types of "Power".  Sauron orchestrated the downfall of Númenor, the most powerful kingdom of Men to have ever existed in addition to most of the powerful Elves of the Second Age.  He also would have defeated Middle-Earth yet again if not for the blind luck/divine intervention of two hobbits sneaking into Mt. Doom.

Sauron was one of the best smiths of magical, powerful artifacts in the history of Middle-Earth, had uncounted armies of Men, Orcs, and other monsters, had spies all over the world, corrupted the leader of the White Council, and drove the Steward of Gondor to madness.

He also lost a fight to a dog in the First Age.  "Most powerful" doesn't necessarily mean physical power.