deidara held back against gaara and he went all out against sasuke . Gaara still would of lost regardless as gaara still struggled against not so serious deidara
False, Garra wasn't going all out either or did you miss the part where Kankorou was talking to their old Sensei who was worried Shukaku would take over. Had he used Shukaku power as he did while he beat part 1 Sasuke and even the small amount of Shukaku chakra he used against Kimimaru then you can maybe say Deidara beat him at his best but that didn't happen. Gaara was actually in the advantage, he took off one of Deidara arm which made Deidara attack the village which caused Gaara to protect and get attacked. Sasuke only beat Deidara because he had the element advantage which allowed him to disarm the bombs, Gaara was actually tanking the bombs with his sand.
Putting Sasuke in Tsunade place? How would he be healing the whole village? He would have to go fight a Pain. Had he ending up against Deva and Asura path with Kakashi then they wouldn't have been going easily as they have been. Deva path could easily have sent Sasuke and Kakashi blasted miles away to kill them or take them out of the fight. If Deva path can send 3 giant toads flying miles away from him and cause them to break their bones then of course Kakashi dying and Sasuke maybe survives by using his CM wings to help protect him.