Oars is Gekko Moriah's most prized Zombie, as he is known to have been an ancient monster that wreaked havoc. He was reanimated after Moriah stored his body and waited for a powerful pirate to arrive that could make Oars into the most powerful zombie. In this case, it was Monkey D. Luffy, who at the time scored a bounty of 300,000,000 Belis. Oars was Moriah's 900th Zombie soldier.
Oars was one of the main antagonists of the Thriller Bark Arc as he nearly defeated most of the Straw Hats and it took Nightmare Luffy even the playing fields. Despite being capable of overwhelming the strawhat crew, Oars was eventually defeated by them, as his spine was crushed and he later had Luffy's shadow ripped out of him by Moriah.
Powers and Stats
Name: Oars (Senior)
Origin: One Piece
Age: Unknown (His age while alive is unknown, but he has been a corpse for centuries)
Classification: 900th Zombie reanimated by Gekko Moriah, in life he had the Epithet "The Continent-Puller"
Attack Potency: City level (One-shot most of the Strawhats and easily overwhelmed Sanji and Zoro's attacks with his own. He should be comparable to Gear 3rd Luffy)
Lifting Strength: Class G+ (Could pick up a large tower, use it as a weapon, and throw it a great distance)
Striking Strength: City Class
Stamina: Possibly Limitless (As a zombie, Oars does not tire, and the only way to stop him from fighting is to destroy anything in his body that is required to move his body parts, such as his muscles, or spine)
Range: Dozens of meters normally, likely over a couple kilometers with Moria manipulating his shadow
Standard Equipment: None notable
Intelligence: Below Average, but due to having Luffy's shadow, he has his personality, and battle experience
Weaknesses: A massive amount of salt being consumed by Oars will remove Luffy's shadow from his body, making his body lifeless
All of Monkey D. Luffy's pre time-skip attacks