IMPORTANT :

1) I completed 300 exam with 170k bp, difficulty was lowered 3 times.

2) Pain-Tendo must have most hp from whole team (Hiruzen will tag him with his insta-ded mystery)

3) Sage naruto must have biggest initiative (if hiruzen is faster then naruto 2nd round then u dont have enough)

4) Your team must have full hp after defeating 1st wave

5) Use Pakkun as support summon.

1st round)

Firemain use mystery.

Firemain must remove Minato's evade with his standard.

Wait for Hashirama to use his Mystery and then use Tendo's mystery on Minato (If tendo is faster than Hashirama then restart and lower his Initiative)

2nd round)

Sage naruto on Hiruzen.

Madara on hiruzen (combo remove hiruzen's mystery)

3rd round)

Minato/Hashirama should be dead if they are not then, you dont have enough power or Ignite + poison did low dmg.

Wait for hiruzen to use insta-ded mystery on tendo if he uses it on other ninja then restart.

4th round)

If Hashirama hit your Firemain with combo chase then restart.

Wait for hashirama to steal 100 chakra then use Firemain shields (+ pakkun will remove edo minato evade)

Sage naruto on Orochimaru then Madara and then Tendo on Edo minato.

Hashirama/Edo minato/Orochimaru should be dead or have low hp with Poison/Ignite if not then restart.

5th round)

Now its only about killing rest ninjas on field with all you got. (There should be Firemain/Lightmain/Hiruzen and Tobirama)