K11 win low difficulty. No point in debating this. As for whether Sakura is the strongest of K11, I do believe she is the strongest, most versatile and third smartest member of K11 so I do rank her higher than the rest especially since she has access to a boss summon coupled with her support abilities. Not to mention her damage output outranks anyone from K11 by far. However, Sakura isn't really the main reason why K11 win. They win due to their teamwork and a wide variety of abilities coupled with overwhelming combinations. Tsunade is superior to Sakura in most aspects and since Katsuyu would be loyal to Tsunade, not Sakura, Sakura is hardly a factor here. Finally, Sakura's fighting style puts her own teammates at a disadvantage while Tsunade herself would have no problem countering any ground disturbances and lethal shockwaves.
As a matter of fact, Neji, Shino and Ino bring more to the table in this battle and will be crucial in stomping Tsunade. Neji's gentle fist, superior speed and taijutsu allows him to seal away Tsunade's chakra points, disturbing her chakra control and weakening Byakogou's effect. Shino's bugs can blind her eyesight, which would give openings to other K11 members, and devour her chakra which further weakens Byakogou. Ino is vital here just in case Katsuyu gets summoned.
