Well, assuming your not limited by tiers, I think sand rush Excadrill takes the cake.
Excadrill@life orb/lum berry
Ability: sand rush
Nature: adamant
Evs: 4 hp 252 atk 252 spd
Swords dance
Earthquake
Rock slide/iron head/shadow claw
X scissor/sandstorm
Preferably you'll have Ttar or Hippo on your team to set up permanent sand, but excadrill can do it himself too. Swords dance is the standard boosting move, doubling his already ridiculous attack, and under sand, his ok speed reaches ludicrous levels under sand, where nothing but opposing sand rush sweepers, deoxys s and extremely fast scarfers will outspeed him. He has good natural bulk so no defensive investment is needed. He doesn't have any real hazard problems, is immune to toxic and thunder wave, and can even learn rapid spin! Just watch out for will o wisp, opposing excadrill, and super effective priority.
Now, lets assume you are limited to Ou. Here's a favorite of mine
Haxorus@choice band
Ability: mold breaker
Nature: adamant
Evs: 4 hp 252 atk 252 spd
Outrage
Low kick
Earthquake/Aqua tail
Dual chop
This is what power is. Sure you may ask why Kyurem B isn't better fit for the job, but with better physical steel coverage and a slight speed advantage, haxorus still has its merits. With decent speed and a monstrous attack, haxorus is a true terror. Outrage and low kick will likely be your main moves, outrage for everthing but steels (and fairies) and low kick for the heavy steels. Aqua tail and earthquake can also nail steel types, and dual chop is good against substitute.
One more: probably my favorite physical scarfer. And, it's UU.
Darmanitan@choice scarf
Ability: sheer force
Nature: adamant
Evs: 4 hp 252 atk 252 spd
Flare blitz
Superpower/earthquake
Rock slide/fire punch
U turn
Darmanitan is commonly seen running a scarf set, and for good reason. Base 145 atk is scary, even unboosted, and base 95 speed, while decent, makes darmanitan quite fast with a scarf. Also, sheer force boosted flare blitz is ridiculously op. Plus darmanitan's powerful you turns allow for easy switches.