Preheat your oven to 350°F (175°C).
In a large skillet over medium heat, cook the ground beef and diced onion until the beef is browned and the onion is translucent, about 5-7 minutes. Drain excess fat.
Add the corn, black beans, cream of mushroom soup, diced tomatoes, chili powder, garlic powder, salt, and black pepper to the skillet. Stir until well combined.
Transfer the beef and vegetable mixture into a greased 9x13 inch baking dish, spreading it evenly across the bottom.
Top the beef mixture with an even layer of frozen tater tots.
Sprinkle the shredded cheddar cheese over the tater tots.
Bake in the preheated oven for 35-40 minutes, or until the tater tots are golden brown and crispy.
Let the casserole cool for a few minutes before serving.