Pokémon Shock Tetris is a Pokémon mini video game released in 2002 by Nintendo. The game was only released in Japan and Europe. It is a variant of Tetris with a few enhancements such as the inclusion of Pokémon themes.
In Pokémon Shock Tetris, blocks will fall from the top and drop to the bottom. In the beginning of the game, each block has four block segments that make up a variety of shapes, though as you progress the blocks will start to have five, thus increasing the challenge (this aspect of the game is not included in most versions of the game). The speed of the blocks will also increase as you play the game. The goal of the game is to make a complete horizontal line. Doing so will remove all of the blocks in that line. You'll have change the direction of the blocks, which is done by shaking the Pokémon mini.
There's a Pokémon twist in this game as one would expect. The player will be able to catch various different Pokémon by clearing lines. Doing so will add that Pokémon to your PokéDex, which the player can view when not playing the main mode. The PokeDex can hold all Pokemon from Generation 1 and 2.