Preheat oven to 350 degrees F (175 degrees C). Line baking sheets with parchment paper.
Whisk all-purpose flour, whole wheat pastry flour, oats, 5-grain cereal, baking powder, baking soda, and salt together in a bowl. Mix butter with white and brown sugar in a separate large bowl until mixture is smooth and creamy. Beat eggs into creamed mixture with an electric mixer until thoroughly combined. Gradually beat dry ingredients into moist ingredients to make a dough. Stir chocolate chips into dough. Drop batter by heaping teaspoonfuls onto prepared baking sheets, keeping cookies about 2 inches apart.
Bake in the preheated oven until cookies are lightly browned, about 10 minutes.