From Bulbapedia, the community-driven Pokémon encyclopedia.
The ZERO-ONE (Japanese: ゼロワン号 No. ZERO-ONE) is an all-terrain safari vehicle designed by Professor Oak. It can acclimate itself to several different environments by using wheels, inflatable pontoons, and jet thrusters for travel over the ground, in the water, and through the air. The ZERO-ONE has no steering mechanism. Instead, it will follow a set path preprogrammed by Professor Oak that takes it to the goal gate. It has an automatic braking system which activates if a Pokémon should get in its path.
Todd Snap rides in it in the Nintendo 64 game, Pokémon Snap. Using the ZERO-ONE, Todd is able to safely traverse the many locations of Pokémon Island. When he shows Professor Oak one of the Pokémon signs, Professor Oak upgrades it with the Dash Engine, which allows it to go faster.
The ZERO-ONE is a random trophy in Super Smash Bros. Melee.
Many wild Pokémon live on Pokémon Island, and avid cameraman Todd uses the ZERO-ONE as his means to get close to them. The ZERO-ONE is fully automated: its progress is monitored and controlled by a series of strategically located beacons. The vehicle can instantly change its shape to allow it to travel by land, water, and air.
One of the main features of the ZERO-ONE is that it can switch modes depending on its terrain. It has a land mode, a water mode, and an air mode. The transformations between the modes are shown when Todd finds the secret exits in the Tunnel and the Valley.
The land mode features three off-road tires, and is used primarily at the Beach, in the Tunnel and at the Volcano.
When in water mode, the three tires are replaced with floatation devices that allow the ZERO-ONE to float over bodies of water. This mode is primarily used in the River and in the Valley.
In air mode, it is capable of hovering in the air by two jets that keep it airborne. This mode is primarily used in the Cave and on Rainbow Cloud.
The Aquamole from Pokémon Ranger, another game by the same developer, bears a resemblance to the ZERO-ONE's water mode, and may have been designed that way in reference to Pokémon Snap.