In battle
Synchronize passes on status problems to the opponent that caused the problem. Synchronize will not pass on the Sleep or Frozen status conditions, or if the status condition was obtained from items such as the Flame Orb. Synchronize will have no effect if the other Pokémon has a type or ability that prevents them from being Poisoned, Paralyzed, or Burned. The badly poisoned condition is passed on as regular poison.
Outside of battle
From Emerald onwards, if the Pokémon with this ability is leading the party, Synchronize gives a 50% chance of encountering a wild Pokémon with the same nature. However, this does not apply to any Pokémon created with Method 1 of the random number generator. This includes Emerald's 'one-off' Pokémon such as legendaries, Castform, and Beldum, as well as Generation IV's roaming legendaries and its non-legendary one-offs, including Bebe's Eevee and the Porygon in Veilstone City.
The ability is also nullified when a Pokémon with Synchronize is strolling in the Pokéwalker.
