In a bowl, combine shrimp, olive oil, lime juice, chili powder, garlic powder, salt, and pepper. Let it marinate for about 20 minutes.
Preheat your grill or grill pan over medium-high heat. Thread shrimp onto skewers for easy grilling. Grill the shrimp for about 2-3 minutes per side until they turn pink and opaque. Remove from heat and keep warm.
If using fresh corn, grill the corn cobs for about 8-10 minutes until charred, then cut the kernels off the cob. If using frozen corn, sauté it in a pan over medium heat for about 5-7 minutes until heated through and slightly caramelized.
In a large bowl, mix together the grilled corn, diced avocados, red bell pepper, and chopped red onion. Season with extra lime juice, salt, and pepper to taste.
In serving bowls, layer the corn and avocado mixture, then top with grilled shrimp.
Sprinkle fresh cilantro over the top and serve immediately. Optionally, serve with tortilla chips on the side for an extra crunch.