Scoop out avocados, leaving a small border. Dice avocado and set aside.
In a skillet over medium-high heat, heat olive oil. Add shrimp and cook until fully cooked through, 5-7 minutes. Let cool, then chop into bite-size pieces.
In a large bowl, toss diced avocado with shrimp, tomatoes, corn, greek yogurt, and lemon juice. Season with salt and pepper. Divide salad among 4 avocado halves. Garnish with basil.