Soul reapers can take out the Ulquiorra and Grimmjow but Kenpachi and Starrk will be trouble.
Tell me the abilities of Isshin's, Unohana's and Yoruichi's bankai first...
Zaraki can solo Unohana. No idea about the others.
If Isshin's bankai is not restricted. Bankai increase power 5-10 times. Shinigami wins.
Tho, if we don't count Isshin's bankai, team 2 wins, but only because of Kenpachi.
Ulquiorra and Starkk are being severly underestimated. Ulquiorra after his reseruccion was already lolstomping Ichigo neg difficulty and after releasing his Segunda Etapa is just became a pointless battle. Starkk defeated hollowfied Love and Rojiro neg difficulty after using those explosive wolves techinque.
Yoruichi is a bad match-up against Starkk, considering she has to go melee and Zaraki was already stronger that Unohana before achieving Shikai. In other words Ulquiorra and Grimmjow just have to buy time, which shouldn't be too hard considering Ulquiorra's strongest abillity is his regeneration. It really depends on Isshin's bankai whether team 1 can win, however since we don't know how strong it is, my vote goes to team 2.
1. I'm not sure what that has to do with what I said. Base Isshin (not even Shikai), is around equal with Base Aizen, Base Aizen 'lolstomped' multiple captains in Gotei 13. Same that captains were able to 'lolstomp' Espada level fighers. So, I don't see a problem with Isshin alone being able to beat all three of arrancar characters in OP.
2. I suppose it's not the topic. But, Zaraki without his shikai, is not stronger than Unohana.
--- He barely surpassed Unohana, but here problem is that he never surpassed full powered Unohana, he surpassed exhausted Unohana, who needed to heal him everytime and she herself was battle worn of previous fight, unlike Zaraki who every fight (and last in which he 'surpassed' her) started healed.
What made you think that base Isshin is at the same level as base Aizen?
Also Unohana stated herself that Zaraki had surpassed her again after breaking all of his inner chains. Zaraki was already stronger then her when she still was the first kenpachi and Zaraki a child. And whether it was an exhausted Unohana or not, how much of a chance does Unohana stand against Zaraki with his shikai?
1. The fact that Base Isshin was able to fight equaly and even overpower Base Aizen.
2. I don't say that Unohana is stronger than Zaraki with shikai.
Aizen at that time already discarded his defence and was at his limits because he was preparing to transform.