Bring a large pot of salted water to a boil. Add the pasta and cook as the label directs, adding the greens to the water. Drain and rinse under cold water; transfer to a large bowl.
Combine the shrimp, red pepper flakes, 1/2 teaspoon salt and a few grinds of pepper in a medium bowl. Heat the olive oil in a large skillet over medium-high heat. Add the garlic and cook until golden, about 1 minute. Add the shrimp and cook until pink, about 3 minutes per side. Add the tomatoes and cook, stirring often, until slightly softened, about 2 minutes.
Add the shrimp mixture to the bowl with the pasta along with the basil and lemon zest and juice; toss to combine.