In battle
If a Pokémon with this Ability uses a move that makes contact, there is a 30% chance the target will become poisoned. In Japanese versions of Pokémon Black and White, this is a 20% chance instead.
This chance applies independently of any moves that may have a chance to poison the target with their own effect. If the attack's target holds a status condition-curing Berry, it is possible for a move's natural effect to inflict a status condition which the target's held item will then cure, only for the target to then be poisoned by Poison Touch. Poison Touch's chances also apply independently for each hit of a multi-strike move.
Poison Touch can poison a target hit by Dragon Tail or Circle Throw. Poison Touch can poison a target with Mummy before Mummy overwrites Poison Touch. Pokémon with Immunity, Shield Dust, or (during harsh sunlight) Leaf Guard cannot be poisoned by Poison Touch, unless the contact-making move is Sunsteel Strike.
In a link battle including a Japanese version of Pokémon Black or White and a non-Japanese version or Pokémon Black 2 and White 2, the chance to poison is determined by the game of the player with the Pokémon with the Ability Poison Touch. As such, a Pokémon with Poison Touch owned by the player of a Japanese version of Pokémon Black or White will have a 20% chance to poison, whereas players of Pokémon Black 2 and White 2 and non-Japanese versions of Pokémon Black and White will have a 30% chance.
Outside of battle
Poison Touch has no effect outside of battle.