Power, ultimate power. This guy is up there with the most powerful of legendaries (Mewtwo, Dialga, Palkia, Giratina, Lugia, Ho-oh, Groudon, Kyogre, Rayquaza, not the incredibly powerful Arceus.) He is there not for incredible stats (which it does have) but for great typing. Mine knows:
Magma Storm: High power, STAB, traps the foe.
Earth Power: Good power, high accuracy, chance to lower Sp. Def. Deals with other Fire types, other Steel types, and Rock types.
Dragon Pulse: Good power, high accuracy, deals with Dragon types.
Flash Cannon: Good power, high accuracy, STAB, chance to lower Sp. Def.