Heat broiler on high. Place shrimp and lemon wedges alternately on 8 skewers.
Halve the squash lengthwise, then cut into 1-inch-thick slices. Divide among the remaining 8 skewers.
Place all the skewers on a foil-lined baking sheet (or place all the ingredients on the sheet if you don’t have skewers).
Brush the kebabs with oil and season with salt. Broil, turning once, until the shrimp are cooked, 3 to 4 minutes. Transfer shrimp skewers to a platter.
Continue broiling the squash until tender, 3 to 4 minutes more. Serve the kebabs with the basil.