Heat the red candy melts according to the package instructions.
Divide the powdered sugar into two gallon sized bags.
Stir in 2 cups of the Chex cereal and carefully mix until all the cereal pieces are fully coated.
Transfer the coated Chex into one of the bags of powdered sugar. Seal and toss to coat.
Spread the coated cereal on a baking sheet to cool.
Repeat the process with the blue candy melts.
When all the Chex have cooled, combine the red and blue cereal with the pretzels, M&Ms, and star sprinkles in a large serving bowl.