Synchronize is an Ability that causes a Status effect inflicted on the Pokémon by another Pokémon to also be inflicted on the aggressor. It has no effect on status from sources besides other Pokémon, such as a Flame Orb or Toxic Spikes. Synchronize also has a 100% chance of making a wild Pokémon the same nature as the user's Pokémon. The Pokémon with Synchronize doesn't need to be sent out, but does need to occupy the first slot in your slot of six. The Synchronized nature is the true nature of the Pokémon, ignoring changes from Mints.