Concept art of an unused sub-boss for Mega Man 10 made with oni themed robots from previous games: Goblin, Oni Robo, Kaminari Goro, and Kaminari Kogoro. Image from the Mega Man Legacy Collection 2 gallery.
Commentary translation from the book MM25 Mega Man & Mega Man X Official Complete Works: "Those mid-bosses are like the culmination of all the oni minions that have ever appeared in the series. They spin around 180 degrees to switch between the red oni face and the blue oni face. The lamp on the middle of the forehead is the weak spot. The player can damage them by attacking when the side of their faces is facing the screen while they are turning."