Cook pasta to al dente according to package directions. Thoroughly rinse cooked pasta with cold water. Drain, and set aside to cool completely.
While the pasta is cooking, prepare the dressing:
In a small mixing bowl, stir together the vegan mayonnaise, dill pickle juice, dried dill weed, and ground black pepper.
Putting it all together:
Into a large mixing bowl, the cooked macaroni pasta, chopped dill pickles, cheddar cheese, and yellow onion. Stir to combine.
Add the dressing and toss gently to coat. It will look like there is way too much dressing. Just go with it and trust the process. The pasta will soak it up.
Cover and refrigerate at least two hours to chill throughout. For best results, refrigerate for 1-2 days.