In battle
A Pokémon with Telepathy avoids all attacks used by its allies in Double and Triple Battles. This includes attacks with multiple targets (such as Discharge), as well as attacks exclusively targeting an ally with Telepathy (such as Thunderbolt). It is, however, limited to attacks, meaning that Telepathy does not protect a Pokémon from its allies' status moves (such as Teeter Dance or Confuse Ray).
When Telepathy prevents an attack from hitting, the message "<name> avoids attacks by its ally Pokémon!" will be displayed.
Outside of battle
Telepathy has no effect outside of battle.