Place shrimp in a large bowl and season with chipotle powder, cumin, paprika and garlic salt. Toss to season evenly.
Heat oil in a large pan over medium heat. Add shrimp and cook, turning frequently, until shrimp cook through and turn pink; about 8 minutes. Set aside.
Place 1 or 2 (stacked) tortillas on a large plate. Place 2-3 shrimp on each tortilla. Top with dressing, avocado slices, cabbage, cilantro, tomato and a squeeze of lime juice. Repeat with remaining tortillas.
Place Greek yogurt, cilantro, garlic, lime juice and salt in a blender or food processor. Blend for 30 seconds. Transfer dressing to a serving bowl.