From Bulbapedia, the community-driven Pokémon encyclopedia.
Pokémon Yahtzee Jr. is a board game manufactured by Hasbro and Milton Bradley. It follows the same rules as the regular Yahtzee Jr. board game, but features Pokémon characters.
A second edition of Pokémon Yahtzee Jr. featuring Generation III Pokémon was released in 2004. A similar game featuring Generation IV Pokémon, entitled Pokémon On A Roll, was released by Pressman Toy, but it does not bear the Yahtzee name.
Playing the game
Pokémon Yahtzee Jr. may be played alone or with up to four players. In a one- or two-player game, each player has five turns. In a three-player game, each person has four turns, and in a four-player game, each person has three turns.
On each turn, a player may roll the dice up to three times. The object is to roll as many dice with the same character on it (Pikachu, Charmander, Squirtle, Bulbasaur, and Jigglypuff), setting aside matching dice and rolling the remainder. Rolling a Ditto on the dice is considered a "wild". A Ditto can be counted as one of any of the other five characters. After the three rolls are finished, the player marks their total score of one Pokémon on the scoreboard with a token. Players may score after one or two rolls if they consider their score satisfactory, however, a score must be chosen after the third roll. Different players' scores are differentiated with different colored tokens.
Rolling five of the same character is called a "Yahtzee" and is the best possible score. Rolling five Ditto is a "Pokémon Yahtzee" and can be scored as a Yahtzee on any Pokémon's scoring field.
At the end of each turn, the player adds their score to the scoreboard. For example, if the player rolled three Charmander and two Squirtle, they would score either three Charmander or two Squirtle on the scoreboard. Scores are final once placed and cannot be added to or removed. Additionally, each Pokémon character can only be scored once. If a score area has already been taken by another player, the token must be placed at the next available open space to the left.