From Bulbapedia, the community-driven Pokémon encyclopedia.
Ride the Tuft (Japanese: そらをわたるピィ Sky-Crossing Py) is the name of a Pokémon-based e-Reader application. It is a mini-game starring Cleffa. Four cards are required to play the Ride the Tuft application: Cleffa, Rattata, Shuckle and Yanma.
In Ride the Tuft, the player takes on the role of a Cleffa. The objective of the game is to jump from tuft to tuft to cross from one side of a cliff to another. If Cleffa stays on a tuft for too long, it will start to fall. If Cleffa makes it to the other side of the cliff, it will move on to another cliff with fewer tufts and the game will continue. If Cleffa falls to the ground (on a tuft or if it misses a tuft) then it loses a life. The game ends when Cleffa loses all three of its lives.