The tiger-masked Obito Uchiha was the Obito Uchiha of the future Nine-Tails' Attack. If Minato Namikaze hadn't possessed the Flying Thunder God Technique and used his battle instincts to outclass that none-too-bright Obito, Obito would have been a nightmare to deal with.
For all its might, Konoha couldn't come up with a way to handle Obito Uchiha.
Kakashi Hatake with two Mangekyō Sharingan had to be from the final battle against Kaguya Ōtsutsuki, when Obito Uchiha had given him a temporary power-up. At that point, Kakashi had inherited Obito's full set of abilities and could use Kamui through both Mangekyō Sharingan.
Kakashi had also received some of the Ten-Tails Chakra left in Obito's body. That let him use Complete Body Susanoo, something an ordinary Mangekyō Sharingan user couldn't pull off even by pushing his eyes until they gave out.
Yet Kakashi Hatake had done it with two Mangekyō Sharingan. If Yi could get some Ten-Tails Chakra from him, that would be quite a prize!
Of course, getting Obito's Kamui would be great too.
Minato Namikaze in his Impure World Reincarnation state was just as powerful. He could fully wield the Yin Nine-Tails' power and enter Kurama Mode.
Under normal circumstances, Minato Namikaze would have been a troublesome Kage Level fighter at most. He excelled at picking off vulnerable targets, but he could still be countered with the right approach.
In Kurama Mode, though, Minato Namikaze had become one of the Shinobi World's strongest fighters.
Of course, Yi was even more interested in the Nine-Tails inside Minato.
As for Yugito, the only thing about her that interested Yi was the Two-Tails inside her.
Yi dismissed Sakura Haruno outright. At this point, Sakura fancied that she had caught up to Sasuke Uchiha and Naruto Uzumaki. That had to be the most powerful