Peixe Balao

This one is fairly simple. The Ultimate Jutsu is the most powerful move you can do in battle.
In order to use the Ultimate Jutsu you must have like 85% of your chakra bar (the blue one). Simply press Y 2 times and then B. If you manage to bring it you will see a mini cut-scene where your character does his/her Ultimate Jutsu.
Now you must do that with 80% of the characters in game.
You can check your progress of that achievement going into "Collection" --> "Ultimate Jutsu Movies".