Place the corn in a saucepan with enough water to cover; bring to a boil. Place a cover on the saucepan, reduce heat to medium, and cook until tender, about 10 minutes. Drain.
Heat the olive oil in a large skillet over medium-high heat; cook and stir the onion and garlic in the hot oil until fragrant, about 5 minutes. Mix the zucchini and tomato into the onion and garlic; cook together 5 minutes. Stir the corn kernels into the mixture; add the poblano pepper. Season with salt and pepper; stir. Cover the skillet with a lid and cook until the zucchini is tender, about 10 minutes. Sprinkle with the cotija cheese to serve.