Suna:
Nagato wins with Chibaku Tensei. Outside of that, Jin Gaara can counter his entire arsenal with CST restricted. CT is Nagato's strongest move so I'm saying Nagato high diff.
Kiri: Nagato wins mid diff. Preta trolls Kisame and Mei, hidden mist is absorbed, and Shinra Tensei, animal summons, and Asura rockets kill them off.
Iwa: Iwagakure wins mid-high diff. Mu and Onoki can counter Bansho Tenin by making themselves too heavy to draw in, and can lighten themselves so when Shinra Tensei repels them, they don't hit the ground as hard. Rain Tiger isn't detecting Muu when they can jinton the rain clouds. Onoki distracts Nagato with jinton, then Muu takes out Nagato with a guerilla tactic (invisible sword to the throat). Chibaku Tensei is countered by jinton.
Kumo: Cloud wins mid diff. With CST restricted Nagato has nothing that can harm BM Bee. Ay goes in for the kill, Nagato repels him with Shinra Tensei, and immediately afterward Bee uses bijuu dama. CT is countered with TBB.
Leaf: Not seeing how they counter CT.