So I'm pretty new to the game, and I am doing a true pacifist run (where you don't deal a single hit of damage). I was wondering how to beat Asgore because he destroys the mercy button. I heard you hurt him until he kneels. Is that the only way?
Unfortunately, the true pacifist run is not available until you beat the game once.
Afterwards, keep in mind that the pacifist route requires you to not gain any exp, so that means you can hit monsters as long as you don't kill them. This means you hit Asgore until you are given the option to spare him. Then, the broken mercy button appears, and you can click on it.