I've beaten this exam at 47500 power with this lineup:


x x x
Chojuro Haku x
AF Ao x


notes: All of them level 85, fully awakened and cultivated, Haku 4 star, Chojuro/Ao 3 stars. Important: Main was hp mooded +45%, total AF hp: more or less 15400.
Talents: 13112, summon: gamaken.
Strategy: Could be you don't win at the 1st try, but within 5-6 tries you should be able to do it.

Round1: Interrupt as soon as possible Kurotsuci, Earth main will use his mystery on Ao. Wait for onoki to kill one of Ao clones and use Haku barrier asap. Let earth main use his standard attack to kill the second clone. Use Main's poison mystery. If one of your ninja dies during this round retreat. You need to get the best combination of double standards given by Onoki/Kurotsuci to win. If they boosts between themselves is the best possible outcome, but is ok also if they use both of their double standards on the same ninja as far as all of your 4 ninjas survive during the 1st round.

Round2: Endure Onoki mystery and use Haku mystery. Thanks to poison and Haku barrier Onoki bomb will be a lot less powerful. Very likely Ao will die. As far as Haku doesn't die before he c*e his mystery don't worry and go on. If it dies retreat.

Round3: Chojuro should have done his work by killing both Crimson Fist and Kurotsuci, poison should have brought Onoki to very low hp. You should have now enough hp to survive onoki hit so that he gets killed by the 4 stacks of poison you were able to apply on him.