Multistrike move
Multistrike moves are moves that strike an opponent more than one time in the same turn. Most multistrike moves will hit the opponent 25 times in a turn, but some work differently. Multistrike moves generally have low base power and imperfect accuracy to compensate for the fact that they hit multiple times. Bide and Counter only take the final hit of a multistrike move into consideration.
Contents
Effect
Generation I
If an opponent is knocked out by a multistrike move, the game does not state how many times the attack hit.
Although only the first strike can be a critical hit, each successive one will deal the same amount of damage. Multistrike moves end instantly upon breaking a substitute. Bide and Counter deal damage based on the last strike alone.
Generation II
If the target faints, the number of strikes is shown afterward.
Each strike has an independent chance of being a critical hit.
Multistrike moves can now continue hitting even after breaking a substitute, then dealing damage directly to the targeted Pokémon. If a multistrike move activates a target's Focus Band, no subsequent hits can knock it out.
If the user is holding a King's Rock, the chance of causing the target to flinch is independent of how many times the move hit (i.e., always ~12% in Generation II).
Generation III
The number of hits is now shown before the target faints.
Color Change will activate after the first hit of a multistrike move, possibly changing the type effectiveness of the remaining strikes.
Each strike from a multistrike move has an independent chance of activating an Ability that activates on taking damage, and each strike of a multistrike move that makes contact has an independent chance of activating an Ability that activates on contact. If a Pokémon using a multistrike move falls asleep or faints between strikes, such as due to Effect Spore or Rough Skin, the move will end immediately.
If the user is holding a King's Rock, each strike now has an independent chance of causing the target to flinch.
Shell Bell activates after each strike, considering the damage from that strike only.
Generation IV
If a multistrike move activates a target's Focus Sash, no subsequent hits can knock it out. Each strike has an independent chance of activating a Razor Fang. Shell Bell activates after the last strike, considering the damage from all of the strikes.
Pokémon with Skill Link will always hit five times when using a 25 hit multistrike move.
Generation V
The number of strikes is now shown after the target faints.
The Focus Sash, Focus Band, and Sturdy need to activate for each individual strike. A Focus Band can still activate repeatedly to prevent fainting, but each chance is independent.
Color Change now activates after the last hit of a multistrike move, so type effectiveness will not change during the attack.
Each individual strike from a physical multistrike move will activate Weak Armor. Each individual strike from a Darktype multistrike move will activate Justified; however, a Grasstype multistrike move will only activate Sap Sipper once. Each individual strike from a contact multistrike move will activate a Rocky Helmet.
Each strike has an independent chance of activating Stench (but this does not stack with the Razor Fang or King's Rock).
Items like Cell Battery etc. activate on the first strike and are consumed in the first strike itself.
Generation VI
Parental Bond turns most singlestrike damaging moves into multistrike moves that hit twice per use.
If a contact multistrike move is blocked by Spiky Shield or King's Shield, the negative effect will only apply once.
Generation VII
Each individual strike from a multistrike move will activate Stamina.
List of multistrike moves
25 strikes per turn
Most multistrike moves will hit an opponent two, three, four, or five times in one turn. These moves are more likely to hit two or three times than four or five, but will always hit five times when used by a Pokémon with the Skill Link Ability.

In Generations IV and earlier, moves in the below list will hit on average 3 times, provided that the move does not miss. From Generation V onward, the average number of hits is now ~3.167, provided that the move does not miss.

 Average power is equal to the move's base power per hit multiplied by the average number of hits, provided that the move does not miss. To take accuracy into account in the average power, multiply the two together (this does not handle modifiers to accuracy and evasion, including taking aim and No Guard).
2 strikes per turn
Several multistrike moves hit an opponent exactly twice in one turn. For the most part, these moves are found on fewer Pokémon, several of them being signature moves, and generally have higher power than other multistrike moves, as they only hit twice. Moves affected by Parental Bond become this type of multistrike move.

3 strikes per turn
Triple Kick works differently than other multistrike moves. It can hit an opponent up to three times per turn, but its base power of 10 will increase by 10 with each subsequent hit, so its first, second, and third hits have powers of 10, 20, and 30, respectively. Also unlike other multistrike moves, each hit has its own accuracy check, and if one hit misses, the entire move ends.

 For Triple Kick, effective power is average power with all three accuracy checks taken into account (modifiers to accuracy and evasion, including taking aim and No Guard, are not considered).
16 strikes per turn
This section is incomplete. Please feel free to edit this section to add missing information and complete it. 
 In Generation II through IV, Beat Up has a fixed power of 10, and deals damage based on a given party member's Attack and level (as if they were using a 10 power move). Despite being a Darktype move, these attacks deal typeless damage, and thus don't take weaknesses, resistances, or STAB into account. The user's Attack stages aren't taken into consideration at all.
 In Generation V on, Beat Up's power is now determined by the base Attack of each party member, a given strike's power being (base Attack / 10) + 5. It is now treated properly as a Darktype attack, gaining STAB and being affected by weaknesses and resistances, and uses the user's Attack stages now.
Trivia
 Double Slap is the only multistrike move with "double" in its name that can hit 25 times.
 Triple Kick is the only multistrike move that powers up on each consecutive hit, and the only one in which subsequent hits can miss.
 Beat Up is the only move that can hit the target more than five times per turn.
This article is part of Project Moves and Abilities, a Bulbapedia project that aims to write comprehensive articles on two related aspects of the Pokémon games. 