People calling Umaga lazy are either seriously uninformed, don't watch wrestling, biased, or just a plain mark. Watch the Cena/Umaga streetfight from the Rumble. That was the best Non-WM PPV main event thus far for 2007. He was fuckin great in that feud and over enough to take the strap for a quick reign before dropping it back to Cena before WM, but instead WWE murdered his heat with the stupid McMahon-Lashley feud and then murdered the IC titles worth with the Santino Marello gayness. He is anything but lazy.
Scott Steiner has been lazy in recent years but to even consider him for laziest of all time is crazy. From 90-92 Scotty was a Top Five worker in the world easy. The Steiners were arguably the best wrestling tag team of the past twenty years and Scotty was the anchor of that team. For all the youngins who haven't been exposed to good tag team wrestling you should dig up some Stiener Bros footage from WCW and their Japan footage is outrageously good. He's far from the laziest wrestler ever.
Khali is severely limited by his size and frame. He isn't lazy, just really useless and limited.
Kevin Nash is a good choice. I'd say Carlito is possibly the laziest wrestler who has potential right now. He was a waste of a Ric Flair program. Hogan was lazy, but a hell of an entertainer nonetheless. Goldberg, The Wall, Mongo McMichael, Sid, El Gigante, Warrior, and Kenzo Suzuki all have legit claim to laziest wrestler of all time.