Zelda II: The Adventure of Link/Dark Link

Traditionally Dark Link is fought by standing on the left edge of the screen and mashing standing stab OR crouching stab.

But the best speed strategies have evolved. Crouching was thought to be better for a while, because we could better control when we hit him. That is important because we could be more like the Tool Assisted runs, and hit him as soon as his invincibility ends.

But many runners intuitively noticed the fight didn't go as well that way. So they preferred standing stabs.

Eventually someone realized that the fight essentially works like the Barba fight: what we do controls what we get. So a pattern was developed to kill Dark Link quickly every time.

Credit to BadBrakes for the strategy, and to Ian "Opus" Napierkowski for the video.