Endless battle

An endless battle is possible using certain methods in the Pokémon games.

In the core series games

Generation I

Transform vs. Transform

In Generation I, if two Pokémon use Transform against each other, they can keep indefinitely transforming into each other, copying each other's moveset (including Transform itself) and replenishing their PP with each transformation. For example, this method works in a battle between Ditto and/or Mew with Transform in their movesets.

Alternatively, this can also be triggered if a Pokémon uses Mimic to copy the opponent's Transform before both Pokémon start using Transform against each other. This is possible due to the fact that in this generation, the player can use Mimic to freely choose any of the opponent's moves to be copied. The Mimic method can potentially work in link battles or in Pokémon Stadium as well, except in those cases Mimic randomly copies one of the opponent's moves instead of allowing the player to choose a specific move.

In Pokémon Stadium, it is not possible to use Transform if the target's current species is Ditto. However, it is still possible to trigger an endless battle if two Mew use Transform against each other. Similarly, if a Ditto and a Mew use Transform against each other, an endless battle is possible once Ditto transforms into Mew. In the earlier game Japanese Pokémon Stadium, there is no limitation concerning the use of Transform.

From Generations II onwards, it is not possible to trigger an endless battle this way. Starting in this generation, Transform fails against a transformed Pokémon (therefore, the first Transform user will be able to repeatedly use Transform and restore its own PP indefinitely but the second Transform user will not be able to transform into the first Transform user). From Generation V onwards, a transformed Pokémon is also unable to use Transform again.

Ghost-type's Struggle vs. Ghost-type's Struggle

In Generation I, if two Ghost-type Pokémon have no moves with PP remaining, they can indefinitely use Struggle against each other. Struggle is a Normal-type move in this generation, which is unable to damage Ghost-type Pokémon. Additionally, when Struggle does not damage its target, the user takes no recoil either.

If two Ghost-type Pokémon have no moves that can damage each other, they have no option but to use those moves and spend their PP before starting to use Struggle.

Poké Flute vs. opponent with infinite PP

In Generation I, the wild Pokémon and non-player character's Pokémon have infinite PP for all their moves. For this reason, those Pokémon will never use Struggle due to lack of PP (although they can use still Struggle if they have a single move affected by Disable).

In some situations, the opposing Pokémon may not be able to damage the player's Pokémon at all, such as in a battle against a wild Magikarp with only Splash, or if the player is using a Flying-type Pokémon against a wild Pokémon that only has damaging Ground-type moves. In those cases, the player can stall the battle indefinitely by using Poké Flute to avoid consuming an item or spending a move's PP.

Generations II and III

Struggle + Leftovers

In Generations II and III, if two Pokémon have no usable moves other than Struggle, it may or may not be possible to indefinitely recover the HP lost by repeately using a held Leftovers depending on the stats of each Pokémon. This is due to the fact that Struggle's recoil is 1/4 of the damage dealt in these generations and Leftovers restores 1/16 of the holder's HP every turn.

In these generations, if two Wobbuffet are holding Leftovers, this causes an endless battle due to Wobbuffet's low attack and high HP. Wobbuffet has no damaging moves other than countering moves, therefore two Wobbuffet battling each other have no option but to spend their entire PP until they start using Struggle. Additionally, in Generation III, their only available Ability is Shadow Tag, which would prevent each other from escaping (the player would be unable to exchange them by other Pokémon in battle). From Generation IV onwards, if two opposing Pokémon have Shadow Tag, they are able to escape the battle nonetheless.

Similarly, an endless battle is possible between a Wobbuffet and a Pokémon with Transform (such as Ditto or Mew), both holding Leftovers, once the latter Pokémon transforms into Wobbuffet as well.

Generation III onwards

Leppa Berry + Recycle or Harvest

It is possible to indefinitely restore a Pokémon's PP in the same battle by consuming a Leppa Berry and restoring this item with the Recycle move from Generation III onwards or the the Harvest Ability from Generation V onwards.

A Pokémon can repeatedly use certain moves to heal itself (such as Recover), or to heal both the allies and opponents (including Heal Pulse or Pain Split), and recover the PP of those moves by using this Leppa Berry.

Alternatively, it is possible to repeatedly recover a Leppa Berry and use Fling to throw it to an ally or opposing Pokémon for the purpose of ensuring that the target will not run out of PP.

In the TCG

In the Pokémon Trading Card Game, there is no known method guaranteed to force an endless battle against the other player's will. If both players agree to have an endless battle, this is achievable by consistently using certain card effects to return the cards to their decks and by not damaging each other's Pokémon or obtaining Prize cards.

For instance, if the only Pokémon used in the deck of both players is Cleffa from EX Unseen Forces, then the only attack available is one that shuffles the player's hand back into the deck. However, it would still be possible to lose this battle on purpose by skipping one's own turns without attacking until one's own deck runs out of cards.