Beat Up (move)

Beat Up is a physical Dark-type move introduced in Generation II.

Effect
Beat Up inflicts damage on the target from each conscious Pokémon in the user's party that does not have a non-volatile status. Therefore, this move can hit up to 6 times.

Each strike has an independent chance of being a critical hit, as well as activating a King's Rock. Beat Up will end instantly upon breaking a Substitute. Bide, Metal Burst and Counter deal damage based on the last strike alone. If Beat Up activates a target's Focus Band, no subsequent hits can knock it out.

Beat Up may continue attacking after breaking a Substitute.

Trivia
In Generation 2, there is a glitch associated with this move that requires being in a Link Battle. One player uses beat up with at least four other Pokemon in their party, but one has Fainted and another has a Status problem. The glitch can cause a de-synchronization between the two games. Check out the Youtube video from Crystal_ for more details.