Deidara and Onoki is a rather deadly combo.
Deidara was capable of evading Shukaku Gaara's massive Sand Constructs fairly easily and Onoki can simply alter the mass of Deidara and his Clay Bird in order to make him faster, making him far more deadly as he can easily outmaneuvor Hiruzen and Danzo's elemental combos. Since Deidara's Clay Bombs aren't dependant on mass rather, the explosive chakra molded within the clay which makes it quite effective.
Because of this, Hiruzen and Danzo's elemental combos will simply not work and Hiruzen, nor Danzo have the speed feats suggesting they can even evade Deidara's C2 bombs. Hiruzen will simply get overwhelmed by Deidara's bombs, Onoki's Jinton or he simply runs out of stamina while Onoki and Deidara can collectively outstall Danzo and eventually identify the mechanics of Danzo's Izanagi due to Deidara's perception of genjutsu (implying he'd recognize that it isn't ordinary genjutsu) or through Onoki's battle experience.
I'm siding with Onoki and Deidara to be honest.