Cook pasta according to package directions; drain, return to pot, cover and keep warm if necessary.
Meanwhile, heat the oil in a large skillet over medium-high heat; saute onion for 5 to 7 minutes or until it begins to soften.
Stir in enchilada sauce, tomato sauce, green chilies, ground cumin and garlic powder.
Reduce heat to medium and simmer, stirring frequently, for about 10 minutes to blend flavors.
Stir corn into sauce and heat through. Place drained pasta in a large serving bowl; pour sauce on top; toss if desired.
Sprinkle with cheese and black olives.