A common technique is a variety of enemies with a variety of attacks.
Soldiers with longswords, soldiers with short swords and shields, soldiers with spears, archers, slings, grenades, assassins with knives, dogs with teeth and claws, horsemen, wizards casting spells, boss brutes with tremendous hand-to-hand strength.
In addition to the methods of attack, mix up their styles. Enemies on patrol, enemies on lookout, enemies milling about. Once detected, enemies that charge directly at you, enemies that team up, enemies that find cover and use ranged attacks.
As you specifically mentioned Zelda, the game has typically always had groups of enemies presenting a challenge, or a single formidable foe by itself. You might get a camp with 3 bokoblin archers on guard, 6 bokoblins with various weapons sitting around a fire, a few moblins with different weapons, or maybe a boss bokoblin leading the group. Other times you'll find a lone lynel with plenty of attacks including element-magic arrows, trampling, spears, light swords, heavy swords, and magical fireballs.
This is an area where composition really helps. You can have a small number of creature types, a small number of attack types, a small number of weapon types, but then when you multiply them together in combinations you get a large variety.