Typically, most buffs are generally 40% this mostly comes from ninjas that use an Auto Barrier at the start of the battle.

This is also the same with most Barrier Ninjas as their mysteries (Such as Sasuke and Gaara).

Then you also have buffs that happen at the start of the battle that will increase by 30% Such as Iruka and Guy. However these last only for 3 rounds.

Then you have your Main Character's talent that uses some kind of enhancement that boosts ninjutsu and attack by 40% for 5 rounds.