Gotta go with Ghost. Barely any of them are physical attackers, and the ones that are (Golurk, Dusknoir, etc.) do not have access to the most powerful physical Ghost-type attack, Shadow Claw (Golurk's Iron Fist powers up Shadow Punch, however).
Official Shadow Crawdaunt of the Pokemon X/Y Boards and Team Miror Infinity "Just because I want absolute power, I'm the bad guy!"
Ghost or Psychic. Ghost has had... Golurk and Giratina? Sure, Giratina's a total boss, and Golurk's okay, but Ghost could use a good physical sweeper or something (I'm probably forgetting a big one, aren't I?). Psychic has had Gallade and Medicham, and both of them were part Fighting, and pretty outclassed.
I'm not easily impressed; I'm usually oblivious to whatever's in front of me. Stunfisk is the epitome of monstrous majestic legendary creatures that spew fire.