Bring a large pot of salted water to a boil.
Add the rotini pasta and cook according to package instructions until al dente.
Grill or sauté the corn until slightly charred.
Drain the pasta and rinse it under cold water to cool.
In a large bowl, combine the cooked pasta and grilled corn.
Add the diced avocado, cherry tomatoes, and red onion.
In a separate bowl, mix the lime juice, mayonnaise, salt, and pepper.
Pour the dressing over the pasta mixture and toss gently to combine.
Fold in the chopped cilantro and chili powder if using.
Serve chilled or at room temperature, garnished with lime wedges.