Legendary Pokémon are not meant to be fought alone. They are meant to be slowly chipped away at by a large crowd of people and slowly succumb to the weight of the Pokémon trainers desperate to take it down.
Youtube user boushinshi has no desire to follow the rules of good sense and decided to take on Legendary Pokémon Moltres with just a friend. Check out this thankfully sped up video of boushinshi rocking Moltres.
(Please visit the site to view this media)
Essentially what is happening here is that boushinshi brought an army of Golems with him to the fight and is throwing them against the wall to pick at Moltres gradually. Because it's a Rock/Ground Pokémon, Golem has an advantage against the Flying/Fire Moltres, and it still takes quite a few of them to make headway against the flame bird.
While it is impressive that boushinshi was able to do this, we have to question if maybe the military strategy of throwing so many pawns at an enemy that they can't deal runs counter to the "bond with your friends" lesson Pokémon has been trying to impart for twenty years.