In a large bowl, whisk together olive oil, 2 tablespoons lime juice, garlic powder, cumin, salt, and pepper. Add chicken and toss to coat evenly. Let marinate at room temperature while you prep the salsa, or refrigerate up to 4 hours.

Heat a dry cast-iron skillet or grill pan over medium-high heat until smoking. Add corn in a single layer and cook without stirring for 2-3 minutes until charred in spots. Toss and repeat until about half the kernels have golden-brown char, about 6 minutes total. Transfer to a large bowl to cool slightly.

To the warm corn, add bell pepper, jalapeño, red onion, cilantro, and remaining 3 tablespoons lime juice. Toss well and season with salt to taste. Let sit at least 10 minutes for flavors to meld.

Preheat grill or grill pan to medium-high (about 400°F). Remove chicken from marinade, letting excess drip off. Grill until deeply browned with good char marks and cooked through, 5-7 minutes per side for thighs (6-8 minutes for breasts). Internal temperature should reach 165°F. Transfer to a plate and rest 5 minutes.

Slice chicken against the grain and arrange on plates. Spoon generous amounts of corn salsa over and alongside. Serve any extra salsa at the table.