Heat the oil in a large nonstick skillet over medium heat. Sauté the scallions until translucent, 5 to 6 minutes. Add the garlic and sauté for 1 more minute, until fragrant.
Add the zucchini and sauté until cooked through but still firm, about 8 minutes. Mix in the corn and toss gently until heated through, 4 to 5 minutes.