I recently passed level 70 Ninja Exam with this Formation:

- GNW Hinata - Pos 2

- Gaara (3 stars or more) - Pos 7

- GNW Sakura - Pos 8

- Azure (with Shadow Clone skills) - Pos 9

+ About the Characters:

- GNW Hinata has the passive which gives her 2 lives, that's how she survive after the Water Boom. Plus, she has the Mystery Skill that gives her 3 times attack.

- Gaara gives a good shield to go through Jiraiya, my shields last even until the Gama. Plus, his Mystery Skill cause huge damage.

- GNW Sakura is the best. Anyone can get her from the Ranked Battle Shop and Arena Shop within the first 2 weeks. Her small Katsuyu will be the bate for the Gama's attack, If some of them survive the attack, they can even heal you.

- Azure needs to get the Shadow Clones Skill + Water Dragon Skill, first to be another bate, second to help kill Jiraiya faster.

+ About the Exam:

- Save all the Mystery for the Gama, Actually, you c*e Hinata and Azure's Mystery when fighting Jiraiya, they will cooldown soon enough. And use Hinata and Sakura's Mystery the first round you face the Gama.

- These Ninjas chase each other so well, that's how you can eliminate Jiraiya fast without using Mystery.

Hope my experience would help!