When absorbing another's chakra, most ninja require some medium through which to do so, whether it be a jutsu (as in several Wood Release techniques), a weapon (notably Samehada and the anime's Infinite Armour), or some other resource (as in the Aburame clan's kikaichū). Others are able to absorb chakra simply by making physical contact with a target. Known indivudals that can do this are: Yoroi Akadō; Jirōbō; Kisame Hoshigaki; all Zetsu; Madara Uchiha; Obito Uchiha; Fūka; the Ultimate Summoning Beast. Orochimaru is shown absorbing only his own chakra from Kabuto Yakushi;so it's unclear if he can absorb all of a target's chakra if he so chooses.