I would like to see this effect Synchronize
From Pokémon Emerald onwards, if a Pokémon with this Ability is leading the party, there is a 50% chance that wild Pokémon encountered will have the same Nature as the Pokémon with Synchronize. Starting in Pokémon Omega Ruby and Alpha Sapphire, this also applies to gift Pokémon in the Undiscovered Egg Group.
Already in the game? It's possible? Maybe in the future?