Kitsu's plot idea

first off an evil organization tried to find a way to control legendary pokemon. after years they sort of succeed. they managed to take the 'hearts' out of all the legendary pokemon in the form of crystal shards. before they could use them to take control of the legendaries the pokemon scattered their own crystal hearts. they are scattered all over Kuro, guarded by wild pokemon. in order to get the crystal shards a person must complete a 'legend quest' and pass many tests before acquiring one of the shards. once the person gets the shard they most choose whether to return it to the legendary it belongs to and free it or keep it to control the legendary (AKA join the bad guys) when all the shards are found and ether returned or kept there will be a big war between the free legendary and controlled pokemon.