Preheat your grill to medium-high heat.
In a large bowl, combine the shrimp, olive oil, garlic, chili powder, cumin, salt, and pepper. Toss to combine.
Grill the shrimp for 2-3 minutes per side, or until they are cooked through.
Meanwhile, make the chipotle-lime sauce. In a small bowl, combine the Greek yogurt, chipotle peppers, lime juice, garlic powder, and salt. Stir until everything is well combined.
To assemble the tacos, lay out the tortillas and top each with lettuce, tomatoes, red onion, cilantro, and grilled shrimp. Drizzle the chipotle-lime sauce over the top and serve.