I mean he was just using his skills + powered up Yamato with fake Shinsuusenju... but actually a Onoki + Tsunade combo with amped Jinton should have been able to wipe him off with ease. Or if everyone attacked Spiral and the Buddha in the time necessary for Onoki to charge and use a Jinton ray. But Onoki himself said that the battle dragged for too long and that they used their best jutsu without results. So how...?