Looking for the one in the main series? See Koopa Clown Car.
Mario Kart series
Mario Kart 7
The Koopa Clown debuted in Mario Kart 7, as a unlockable kart body part. The Koopa Clown offers a boost in handling, but lowers acceleration and off-road. In terms of hidden stats, the Koopa Clown offers a boost in sea and air handling, as well as mini-turbo.
A computer-controlled Bowser may use the Koopa Clown kart body, usually equipping them with the Roller tires. A computer-controlled Mario and Lakitu also have the tendency to use the Koopa Clown body, with Mario equipping the Koopa Clown with Roller tires, and Lakitu may equip the Koopa Clown with the Monster and the Swooper (Swoop) glider.
It is also used for the Expert Staff Ghost for GBA Bowser Castle 1, using Bowser with the Roller tires and the Super Glider. It is also used for the Expert Staff Ghost for Wii Coconut Mall using Honey Queen, equipped with the Sponge tires and the Paraglider (Parafoil).
Mario Kart 8 Deluxe
The Koopa Clown reappears in Mario Kart 8 Deluxe as an unlockable kart body part. Unlike in 7, the vehicle itself now has shorter exhaust pipe in the rear. A side panel on both sides pop open to reveal small propellers when the Koopa Clown is in anti-gravity and gliding sections. A larger propeller also comes out from the bottom when the vehicle is in said sections. In terms of stats, the Koopa Clown has a huge reduction in acceleration and a slight reduction in speed.
Mario Kart Tour
The Koopa Clown returns in Mario Kart Tour, where it is classified as a Super kart. Peforming Mini-Turbos with the Koopa Clown will earn more points. It retains its design from Deluxe, equipped with the Standard tires from said game. However, unlike in Deluxe, it's rim does not change color for the Koopalings, sticking with the default green rim. There is also a dark variant, simply named the Dark Clown, which is also classified as a Super kart.