Jumpy Koopa is the nickname given to a hyperactive green Koopa Troopa. He jumps around a lot and imitates Mario's other moves as well as using power-ups and other forms of combat. He is actually one of the plumber's more formidable foes.
Once, as Mario was about to stomp on him, the Koopa panicked and disobeyed Bowser's orders to "[m]ove to the left", instead dodging the hop, removing and throwing his shell, and performing a jump of his own to finish off his red-clad opponent. News of the feat quickly went viral. When Bowser heard of it, he was not angry, but rather, impressed, and increased "Jumpy"'s rank to Koopaling.
Jumpy tends to move around with great speed and agility, and in tense situations doesn't think before he acts. While he has some sense of humor left, his training and position have started to shape him into a ruthless killing machine who bars no holds when taking down his enemies.
Jumpy appears as the protagonist of Jumpy Koopa's Tower o' Doom!. He is also set to have a role in New Super Mario World as a recurring boss. He also appears in Super Mario: Elemental Journey as a boss on Koopa Island Galaxy with a slight redesign. He now wears red shoes with a Red J on them, similar to Mario's cap. He also has four black scales protruding from his head.