Deva's ability is in direct correlation to nagato. A tired nagato lost, and only after he defeated the entirety of the leaf village and sage mode naruto.His Deva path was still capable of combating Naruto though. Only reason he lost was Naruto outsmarted deva path. Pain was actually out smarted quite a few times in the series. Displaying a lack of battle intellect in my opinion. The fact that he tried to out muscle the nine tails jin is proof of that.
And chibaku tensei is a seal, he tried to seal ninetails.
Matter of fact: Why didn't he just kill Naruto and revive him later like Kabuto planned on? Or simply revive him like he did the village? Plot i guess but since we are discussing i shall contribute it to lack of intelligence lol
Thats stupidity on kabuto's part not nagato's. If the host dies then beast dies too and then revives outside the jinchuriki, had kabuto killed naruto he wasn't getting kurama. kurama would have revived elsewhere.