Kabuto w/ the soldier pill (something in his arsenal, a tool so it goes here) was taking on Tsunade in Taijutsu when she had her seal and overwhelming her. Tsunade may not be as rusty as she was in Part 1, but you restricted the seal altogether and we saw how much stronger, faster and how much more chakra Sakura got just from forming said seal.
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but her powered up punch sent it
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and then she caught up to that and her strike is far stronger than it was as we all know.
That is from simply forming the seal. Taking that advantage away from Tsunade is most likely a far greater demerit than making her rusty. And she has no monster strength on her own btw, that's all CES as Databook 2 states. Only thing you can debate her being superior or equal to in is more stamina, and even that is probably wrong.
So with that being said, Kabuto does her like he did her back in Part 1. Only way he loses is if the gap between Tsunade's skills in Part 1 and Part 2 is so large that it circumvents the vast decrease in strength and speed. Which it doesn't imo. Just look at Sakura pre Seal and post Seal. All her good reaction feats come from moments after she awakened her seal. Before she was below average in that category.
And that's me not even taking into account the fact that Kabuto in Part 2 has a better chakra scalpel. That's not me taking into account that Kabuto's chakra scalpel can actually cut things like wood and flesh by the time Part 2 has rolled around.
Btw, are there any panels that actually say that Tsunade was rusty besides that Kabuto panel?