Kabuto and Orochimaru would win low-mid difficulty.
-White Rage plus a finisher of choice would end Onoki's life, though Raikage would survive since Kabuto can't physically hurt him.
-Orochimaru has Zetsu abilities, so he should be able to absorb the Raikage's chakra since they can't really hurt him, Kabuto can paralyze him with Sound Genjutsu to make an opening for this.
Manda II isn't really important here as it can't hurt the Raikage and Onoki can be taken out without the need of Manda II.
onoki turns third raikage into a flying superman style juggernaut, while producing rock clones and jinton. jintons one of the few things that can kill oro and i doubt he has the speed to dodge it. then DSM kabuto is beaten down