Re: Let's get something straight.
Er, why would Pain randomly know what's going on? The point is, most shinobi will naturally let their guard down when they think they've killed their opponent. Nagato isn't someone who has knowledge on forbidden Uchiha techniques (from what we know), so he has no reason to suspect that Obito has a way of making disadvantageous moments mere illusions. Seeing chakra with the Sharingan didn't stop Sasuke being taken aback initially by Danzou. The Rinnegan can see chakra, suggesting it can do anything else is simply speculation.
Originally Posted by iSpeak the Truth
His body isn't there, so it won't work. Quite frankly, that's like saying Shinra Tensei can be used on someone if their body is in a completely different country. There's nothing there to affect with gravity.
Regardless, it's a jutsu and his image still appears in that plain. Pain has the ability to repel and attract all physical forms and and all manner of jutsu. It is the reason Yahiko Path was called GOD MODE, it's like having a power God himself would have.
That dog can still be incapacitated (as we saw with Amaterasu), so being pierced with multiple Mokuton spikes isn't something it can freely tank without consequence. Obito just knows everything because of Madara, that's why he's such an effective fighter.
Except for the one that keeps multiplying when you hurt it(Cerberus), that's all he really needs. Knowledge of God cannot contest the power of God.