Mario Kart
Blue Thunder: A thunderbolt that affects only the leading racer.
Rainbow Spiny Shell: It flies across, to a random racer, and makes a large rainbow explosion!
Koopa: It runs around randomly when deployed.
Original Mario games
Coin Leaf: It turns you into a tanooki form, and automatically adds to your coin count when in use.
Koopa Powerup: Turns you into a Koopa for a limited amount of time. Enemies mistake you as a real Koopa. It lasts for 10 seconds.