Combine oil, vinegar, salt, pepper, zucchini slices, and yellow squash slices in a large bowl, tossing gently to coat. Place squash mixture on grill rack coated with cooking spray; grill 2 minutes on each side or until tender.
Reduce grill temperature to medium.
Lightly coat pizza crust with cooking spray; grill 1 minute on each side or until lightly toasted. Arrange zucchini and squash over crust. Arrange tomatoes over squash; sprinkle with pecorino Romano cheese. Grill 5 minutes or until thoroughly heated. Remove from grill; sprinkle with basil and oregano.