Long ago, when humans first started to tame Pokémon, the world had not seen war for hundreds of years. The world was a peaceful and prosperous place. But all of this happiness needed a source. That source was Ho-oh, the guardian of all Pokémon. Ho-oh brought with it great abundance to the world. When humans first realized that Pokémon could be trained to assist with helpful tasks, the world advanced. Time flows on, and technology advances. As kingdoms grew, so did potential sources of conflict. All that was needed was a spark to begin a conflict. Then...it happened.
A massive war broke out between two of the greatest kingdoms, and the Pokémon were turned against each other. Shortly into the war, both sides discovered that Pokémon were excellent fighters. More establishments were drawn in and defeated quickly at the hands of the Pokémon. As the war drew on, the units left had stronger and stronger Pokémon. The powers of their Pokémon became so strong that much of the population and establishment could be wiped out.
When all hope was lost, three mysterious warriors rushed in from the horizon, each mounted atop a large beast Pokémon: one a tiger with lightning-bolt stripes, carrying with it storm clouds; another, a tough, fire-spewing lion-like creature; another, a blue cheetah-like creature with an icy crystal on its head. The beasts could run far faster than any horse man had known, and attacked viciously, using the elements of fire, water, and lightning.
These three brave warriors stayed true to the Pokémon. They were known as the Beast Riders. After the war had reached its climax, they rode throughout the land, spreading justice and peace, just as Ho-oh did. Upon their return to Tin Tower, they met Ho-oh for the first time, and swore upon their lives to guard it forever. But the people thought they wanted war. What was left of the armies of trainers stormed the Tin Tower, killing the three warriors and their legendary Beasts. After the army retreated, Ho-oh flew above the tower, weeping in memory of the three brave warriors. This all happened about seven hundred years ago.
Just a scant thirty years later, Ecruteak's Brass Tower burst into flames as a result of lightning striking it. Lugia, the legendary bird Pokémon that was said to roost atop it, fled to the southwest swiftly, never to be seen again. The fires raged for three days and three nights, causing the tower to collapse into the ground. After the three days and three nights, a miracle befell the city: a torrential downpour put out the flames, revealing a smoldering ruin of what was the home of Lugia.
When the downpour ended, Ho-oh flew above the ruins of the tower, shining a rainbow straight into what was left of the tower basement. This light branched off into beams of yellow, blue, and red. As the different lights changed shape, it was evident what Ho-oh was doing: giving new life to the legendary Beasts that sacrificed their lives for Ho-oh. However, the revived Beasts were but dwarves of their former selves. In times of trial and tribulation, three warriors chosenby Ho-oh will ride across the land, quenching war and promoting peace. They are the Beast Riders, and they are the guardians of Pokémon.