I dnt think sakura has traind like lee did in 3 yrs as an adult and rocklee is a total beast who was underplayed by kishi
What makes you think that? Maybe she wanted to become even stronger since in the war she couldn't heal Shikamaru while Tsunade came and healed him like nothing and she couldn't really help Naruto and Sasuke against Madara, that could be what makes her train as she did with Tsunade for the 2.5 years. Before it was to get strong to help Naruto save Sasuke and to stand along side Naruto and Sasuke which she did but couldn't fully do.
Lee would want to train to be able to go the last 2 gates since he couldn't fight along side with Gai against Madara (he still helped Gai) but seeing how the 8th gate left Gai might make Lee not want to learn the 8th gate since he knows the sadness he felt for Gai at the time and might not want to have those who care for him watch him die. Lee would of course train his body, improve his taijutsu and weapon skills but he will still feel fatigue from using the gates, he might not for the lower gates but he will for the higher ones like Gai feels the 7th gate and his body is highly trained so Lee should still feel 6 and 7 gates of he gets 7 gates in the movie.
Sakura is already stronger than Lee, he go 5 or 6 gates and attack her and she heals from that and after using his big attack in gate 5 or 6 then his body will be weakened and it takes 1 hit to kill him. Yin seal can heal body parts and organs as Tsunade told Orochimaru in part 1 and Madara said Sakura had it when he stabbed her. In the time skip Sakura will surpass Tsunade most likely in medical ninjutsu and strength since she was pretty close to her already in the manga (able to use remote healing which shizune couldn't learn). She's train to have great evasive skills which she showed against Sasori and would probably improve on that, she was a genjutsu type so might learn that, she already uses sleeping gas and poisons kunai's so Shizune might teach her the poison gas she spit out at Kabuto in part 1.
Basically Sakura is already ahead and would just keep improving. She wants to surpass Tunade, a Kage level. Lee wants to surpass Gai who is jounin level base. Lee base is currently Chunin so in the last his base will be Jounin no doubt as would other K12 members. Naruto and Sasuke base are already jounin so I see Naruto base being Kage and idk if Sasuke trains his base or just goes off to master his EMS and Rinnegan (he haven't trained his base in Shippuden since absorbing Orochimaru).
Sakura will be the strongest, 3 years gives her 3 years of chakra being sealed in her yin seal again but her base chakra would also improve plus currently she punched the grow with the Yin seal closed and Hashirama compared her strength to Tsunade but we see Sakura opens the yin seal to access all of its chakra to heal the alliance and when she was going to hit Madara so she was most likely using more chakra against Madara which limbo blocked.
