An Air Ride Machine is a vehicle (usually an aerial one, hence the game's title) that Kirby can ride in Kirby Air Ride. They usually move at average speed, except for the Legendary Machines, and can usually fly very well.
In Kirby Air Ride
See Kirby Air Ride.
In the anime
Air Ride Machines also make an appearance in Kirby: Right Back at Ya!, most notably in the final episode. In the final episode, they are used primarily by Nightmare Enterprises, but some are put into use by Kirby after their riders are defeated. The Air Ride Machines included in the anime are the Formula Star, the Rocket Star, the Winged Star, and the Shadow Star. All four Air Ride Machines in the anime are also in Kirby Air Ride, with more content in the game than in the Anime, contrary to most things in the Anime.
It can also be noted that the Air Ride Machines were said to have been stolen by Nightmare from the Star Warriors that fell in the battle between the Galaxy Soldier Army and Nightmare Enterprises. According to Kabu, from what he has learned from the other Kabus throughout the universe, Nightmare has been stealing these Air Ride Machines from all over the universe. Because he knew this, he knew that Kirby must learn to fly not just Warp Stars, but other battle vehicles like the Air Ride Machines as well. Therefore, he sent him and Tiff a dream where Kirby received his dream training, which later paid off in the final episode when he stole a Winged Star from a Winged Star rider as he fought to prove what a true Star Warrior he was to everyone (because King Dedede and Escargoon sent and told him to do so and open the gate leading into the main interior of Nightmare's Fortress).