Preheat grill to medium heat or oven to 400°F (200°C).
Bring baby potatoes to a boil and cook for 8–10 minutes until slightly tender.
Drain potatoes and place them in a large mixing bowl.
Add shrimp, sausage, and corn to the bowl.
Drizzle olive oil over the mixture and sprinkle Cajun seasoning, garlic powder, paprika, salt, and black pepper.
Toss everything until well coated.
Divide the mixture evenly among foil sheets.
Fold foil tightly to seal each packet.
Grill or bake for 18–20 minutes until shrimp are cooked through.
Carefully open foil packets and drizzle with lemon juice.
Garnish with fresh parsley and serve immediately.