Simple: Its stats are twice as affected by modifiers (Swords Dance raises 4 ATK stages instead of 2, Tail Whip lowers 2 stages instead of 1, etc).
Download: Upon entering battle, ATK rises one stage if the foe has less DEF than SP.DEF. Otherwise SP.ATK rises one stage.
Unaware: During damage calculation, ignores foe's stat changes except SPEED.