Hoohoo is an owl-looking robot that appeared on Mega Man 9.
Those enemies are aerial and hold a rock that they throw before the player. The rock they throw can be either of earth or of ice, and if it touches terrain, it can leave debris. The debris harms the player character upon contact. Both the rock and the debris can be destroyed by the player's weapons, and can leave pickups. If the rock is released in terrain, it will crash immediately.
When flying, they will move in a set direction and stick to it, going slightly up and down in the shape of a wave and ignoring any terrain collision. In the Level Builder, its direction can be set. There is also an invisible Spawner, which will make them appear undefinedly if the player is on the spawner's area.