The Scarlet Wollywog is, like many red-colored frogs that humans know, poisonous. However, you would not know it unless you read it in a guide; it is only poisonous to those that eat it. Since pikmin don't eat the Wollywog and onions are not affected by toxins in what they process, the poison in the Scarlet Wollywog does not affect game play in the slightest. For all the players care, it is just a recolor of a Yellow Wollywog with a tongue. the tongue is used to eat pikmin but it can only eat one at a time and most of the time they just happily hop around ignoring pikmin. they seem to always have there tongue sticking out.