Iggy Koopa is the crazy lanky green-haired Koopaling and an ally of Bowser. In SMG4, he makes several cameos but his most major appearance is in SMG4: Stupid Mario World where Bowser Jr. sends him to Yoshi Plains to defeat Mario and Yoshi. As they're walking through the plains, they encounter Iggy in his Clown Car shooting Bullet Bills at Mario and Yoshi. Mario had Yoshi swallow all the Bullet Bills and shoot them all back at Iggy Koopa defeating him. After his defeat, they made their way to Donut Plains Haunted House.
He was one of the Koopalings that attempted to get their hands on Smash Bros Ultimate.