One of the hardest things for developing authors to grasp is the idea that the villain is inherently stronger than the hero. The reason this is so hard to swallow is because a story is supposedly about the hero, and most developing authors, particularly in the fantasy and sci-fi genres, are looking for heroes that are more than mere protagonists, but are unique and outstanding individuals who are probably misunderstood and definitely have a wealth of power or skill in them that cannot be matched by any individual.
This is where things get hard for the author. The heart wants what the heart wants, and if the heart desires a powerful protagonist it feels antithetical to that desire to create an even more powerful antagonist. It doesn’t have to. Of course, the other side of that coin is the David and Goliath/Tortoise and Hare conundrum. In these classic tales an obviously powerful antag is defeated by a protag with minimal skills and a lot of heart and patience. This dichotomy feels to me as false as the all powerful hero, and it is explained by Proverbs 16:18 which says something along the lines of Pride goes before destruction. In other words, the antag screwed up so royally that it left an opportunity for the underdog to succeed. Most writers I work with aren’t writing that story. The story they are writing is about the superman-esque character, and they cannot find their Luthor.
A villain has to be strong where the hero is weak. They need to be willing to take chances and do things a hero would never try. The reason the Joker is such a great foil for Batman (not the Affleck Batman, because that is just nonsense. Heath Ledger would kill himself again over that noise) is because he is willing to do and act in ways Batman ever could. So, even if your hero is powerful in one way, there is always a way they are weak. That is where you find the strengths of your villain.
And you better make those strengths more powerful than your hero can possibly imagine.