Object pooling with different type of enemies problem. C#

Hello guys, It's the first time I do object pooling so i'm trying to learn the basics. Until now i always instantiated and destroyed enemies when they spawned/died. I read that doing this it's not well optimized and it's better using object pooling. Enemies data are ScriptableObjects, and i've got a level (scriptableObject too) that has got every enemy that should spawn inside that level. This is what i have done until now:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
  
  
 public class EnemySpawnScript : MonoBehaviour {
     
     #pragma warning disable 0649
     private GameObject enemy;
     #pragma warning restore 0649
     public void enemySpawn (LevelData level){
         //here I loop for every ScriptableObject inside the level to instantiate the right prefabs.
         foreach (EnemyDataSpawn enemyDataSpawn in level.dataSpawner) {
             StartCoroutine (InstantiateObject (enemy, enemyDataSpawn));
         }
     }
  
     IEnumerator InstantiateObject (GameObject enemy, EnemyDataSpawn enemyDataSpawn){
         LevelManager.previousEnemyDelay += enemyDataSpawn.delay;
         yield return new WaitForSeconds(LevelManager.previousEnemyDelay);
         enemy = Instantiate(Resources.Load("EnemyPrefabs/"+enemyDataSpawn.enemy.enemyID)) as GameObject;
         enemy.name = enemyDataSpawn.enemy.enemyID;
         enemy.transform.position = enemyDataSpawn.spawnPoints;
         EnemyScript.InitializeEnemyData(enemyDataSpawn);
     }
 }

I do "LevelManager.previousEnemyDelay += enemyDataSpawn.delay" because I want that every enemy spawns with a delay (set inside the enemy ScriptableObject that now i call enemyDataSpawn) that begin when the previous enemy has spawned. Now i've studied a little about object pooling and I was able to use it for the player bullets following the unity video tutorial about pooling. The question is: how can I do object pooling with different types of enemy that should instantiate in a precise order (that can be modified in the future, so i cannot know how many enemies, what kind of enemies will spawn, etc), exactly like the code above(but using the pooling technique, without instantiating and destroying everytime)? Thank you in advance.