Ultra instinct is the current top going form in dragon ball super. Goku is the first one attains the form but not yet mastered it during jiren and kefla fight.
In last episode, we learned quite a bit about this state. We found out that although Goku is good at defense, he is struggling with the attacking part of the game with this form. That is why some of his attacks weren’t initially that effective against Kefla. So Goku needs to have more control or mastery over attacking while being in Ultra Instinct, but as we saw Goku ran out of energy after the encounter. Also he is constantly being targeted, and also after ultra instinct Goku beome tierd time limit Goku might .Sure he can get better, but the defense came to him naturally, not aggressiive in attacking. Remember that in all these years even Beerus couldn’t master Ultra Instinct completely, it’s not easy.
Ultra Instinct Vegeta ,he attains Ultra Instinct ,Goku’s Ultra Defense and Vegeta’s Ultra attack would be a perfect combination to combat Jiren and other opponents in order to win The Tournament. Such a contribution will be able to satisfy all the fans, because whenever Goku alone nails the deal hardcore Goku fans likes it but hardcore Vegeta fans gets upset. Also when Vegeta loses and Goku nails the deal, Hardcore Vegeta fans get upset.
Complete each other in order to save their Universe will truly do justice to these characters, make sense in the plot, keep the fans happy and most importantly despite defeating Jiren, he will still continue to be a legit threat. Because if they defeat him in 2 vs 1, it would still mean Jiren is stronger than both of them, but any of them might not have to be defeated. Universe 7 surviving till the end, while Jiren is still in the stage, can still win, if U7 outnumbers them in terms of survivors.
There are a lot of epic ways of playing this Goku-Vegeta team up. One obvious idea would be fusion resulting in Vegito or Gogeta. This would combine attack and defense, and also multiply their power at the same time. Plot wise this is a legit possibility because we now know Potara is allowed in the tournament, and Universe 7 even has the potara ready. All that needs to happen is Goku and Vegeta asking for it. Given they brought back fusion last arc, and it only lasted for a while they might just use it again to keep the fusion popularity up, and this would be resourceful for merchandise selling too.
I want to talk a bit about Goku lacking in Ultra Instinct. When Goku is under attack, he lets his instinct take over him, and the body dodges and defends automatically. However, when it comes to attacking, Goku can’t help but think about it, he ends up using his mind to come up with attacks. Thus, his offense is not able to make full utilization of Ultra Instinct. Even if you look at how he unlocked the form, it might be telling us why he is better at defending now. Whis explains it as- “The energy of the spirit Bomb must be acting, as a temporary source of power for his depleted body. However, the main point is something else. In that big explosion, the raging power of the spirit bomb that entered Goku, and Goku’s own power to resist it. Beyond that clash of power, Goku broke through the shell to the deeper potential within himself.” This was kind of foreshadowed in that pre-tournament episode, where Frieza trapped Goku in Hakai, even there he desperately defended himself from the Hakai annihilating him. So, when Goku unlocked the form he was more in a defense position, trying to protect himself, which could’ve ultimately triggered his defense better.
So, I am thinking if Vegeta gets it, And Vegeta always looked like the more attacking guy.