I think A would win on his own if i'm honest... there's no doubt im my mind Kakashi would beat Darui but i think in the time it took Kakashi to hit Darui with Kamui it would be possible for A to kill him as he completed the attack.
And then A's immense speed and strength, enhanced by his lightning cloak which sasuke's chidori could barely puncture, would be able to destroy Tsunade even if she used her mitosis regeneration.
Tsunade is a legendary medical type, thats about it, do you honestly think A would have stood by as Pain destroyed his village?