Whopper

Whopper (ワッパー) is a sub-boss in Mega Man 4, and like Kabatoncue, there are two of them in Ring Man's stage. It is vulnerable when its eyes are open, but that is also when it launches its rings in six directions. A few charged shots will destroy it easily. Two Drill Bombs or one charged Pharaoh Shot will also work. The Flash Stopper can be used to freeze time, and take the Whopper down easily, but the rings that were launched will still damage the player if they are touched.

Trivia

 * Whopper is referred to as "Spring King" in Nintendo Power issue #32.