How to generate different diagonal platforms?

I'm making this game where you have slide down platforms (that are parallel) but had problems with generation. I made a little script that generates 10 of the same platforms parallel. But how do I randomly instantiate other prefabs? I tried with a random number generator and if statements but then the platforms wouldn't be parallel anymore.

 [SerializeField] private Transform platforGen1;
 [SerializeField] private Transform platforGen2;
 [SerializeField] private Transform platforGen3;
 [SerializeField] private Transform platforGen4;

 [HideInInspector] private float nextPlatformYCord = 0f;
 [HideInInspector] private float nextPlatformXCord = 0f;
 private float numOfPlatforms = 10f;
 int x = 1;

 private void Awake()
 {
     do
     {
         SpawnPlatforGen1(new Vector2(10.33815f, -3.778132f) + new Vector2(nextPlatformXCord, nextPlatformYCord));
         nextPlatformXCord += 16.31f;
         nextPlatformYCord -= 10.49f;
         x++;
     } while (x <= numOfPlatforms);


     }
 private void SpawnPlatforGen1(Vector2 spawnPosition)
 {
     Instantiate(platforGen1, spawnPosition, Quaternion.identity);
 }