Combine oil, vinegar, salt, pepper, zucchini, and squash in a large bowl, toss to coat. Place the mixture onto a sheet of foil and wrap it up and secure. Then, place it on the grill and grill for 2-3 minutes on each side or until tender.
Place the pizza crust or dough on a sheet of foil sprayed with cooking spray. Place the foil on the grill and grill for 2-5 minutes until the bottom is done.
Carefully flip the pizza over removing from the foil. At this point the uncooked side should be facing up.
Arrange the veggies on the pizza along with the tomato slices.
Add the basil and cheese. At this point you can also add additional garlic salt if you prefer it.
Cook another 2-5 minutes until the bottom is done and cheese is melted.