Who were Zetsu's biggest enemies?

[SeveN797]

Well Canonically Tobi as Obito would have to give up the power, because he was dealing with both Sasuke and Naruto as Jyubi jinchuuriki giving the alliance no hope until he let the bijus free. And if Nagato did not sacrifice himself to the leaf but to Madara instead, Madara would be alive with both his eyes back in his sacket after taking it from nagato.
It's not like anybody but edo madara was using the rinnegan in the war anyways since Tobi couldn't use it. He was fighting two perfect jinchuurikis with just kamui and other skills alone. It was Shisui's eyes that he was risking his life for after hearing about Nagato's death, so with nagato being alive he wouldn't of needed to sacrifice his eyes in the first place. He wanted EMS Sasuke because he implanted him with EMS and he wanted BM naruto to happen.

There's also a possibility that nagato would've been able to bring akatsuki back if he was still alive.

Yeah but seems you lost my point. For example Nagato using rinnei tensei for Madara is as I said a different scenario and there's no point in discussing those. My original point is that Rinnegan was the most important thing in BZ plan, hence the owner of Madara's eyes - Nagato could become BZ biggest enemy if he betrayed him and Obito.

 

[Rikudou Tobi]

Yeah but seems you lost my point. For example Nagato using rinnei tensei for Madara is as I said a different scenario and there's no point in discussing those. My original point is that Rinnegan was the most important thing in BZ plan, hence the owner of Madara's eyes - Nagato could become BZ biggest enemy if he betrayed him and Obito.

Nagato would need to gouge his eyes out for BZ plan to fail. What I'm trying to tell you is that the worse possible scenario besides the eye gouging already happened.
Like I said before, Tobi already can already use the gedo mazou without the rinnegan, him and madara. Once the bijus chakra is collected inside the statue, rinnegan or not the Jyubi is formed. Kaguya=Jyubi=God tree, it's up to zetsu to turn the caster of IT into kaguya after the genjutsu is in place.

Once gedo mazou touched earth it was all over. Syncing the two Uchihas up the the statue was just an alternative to Kaguya's revival just in case something bad happened to Nagato. Even the six path jutsus that Black zetsu left for madara and obito to use were all jutsu to insure Kaguya's revival.
Rikudou jyubi coffin seal, Gedo art rinne tensei, absorption,Gedo black receivers, Gedo chakra chains, Summoning art: Gedo mazou phantom dragon???
He handed them the blue prints into reviving Kaguya.

 

[SenseiSama]

Itachi played a vital role in the Uchiha genocide. All of the Uchiha were victims of BZ's machinations.

Itachi's actions brought balance to the force, the new generation Uchiha will be free from the Curse