Things You'll Need
Instructions
Travel to Mt. Coronet in the center of the Sinnoh region. Make your way up the mountain.
Walk to the Spear Pillar at the mountain's summit. Approach the symbol between the two pillars.
Press "Start" to bring up the in-game menu and open your "Key Items" bag. Select the "Azure Flute" to play it and reveal a never-ending staircase.
Follow the staircase onto the glass platform above the Spear Pillar. Approach Arceus and press "A" to challenge it to a battle.
Fight Arceus with your strongest attack moves to lower its hit points as much as possible. Fighting-type moves are super-effective at lowering its hit points into the red zone. Be careful not to make Arceus pass out.
Throw your strongest Poke Ball, such as a Timer Ball, Ultra Ball or Master Ball, at Arceus to capture it. Continue throwing Poke Balls if it breaks free.