Get more battle power or a stronger team (blitz usually work well).

Or you wait for level 88+, when it becomes easier (they are parametrized by level), or you just need an higher power. At your power you can beat it only with han, azure fang, sailor sakura and a 3rd healer.

No one have mentioned any of these points before, so here goes:

1. Don't forget buff removal (Han, or Wind main's Wind Dust Mystery if you're poor like I was when I was doing it ages ago). The reason why The Final Trial is so hard is because the Pains buff the crap outta each other, you remove all those buffs, and they hit like little girls.

2. Clone tanking: Have clones tank all the dmgs by having ninjas that makes clone and ninjas that can shield them. Back when I was doing Final Trial, I used Wind main, Sage Naruto, Iruka, and Gaara.

3. Prioritize and focus dmg. Don't just aimlessly atk them, kill them one by one in order of importance. Interrupt/cc whenever need be.

I used this team when I did it. I had 47.5k at the time.

https://www.youtube.com/watch?v=9MC7V19BN6s

It's a bit outdated with the changes we've had since, it didn't work for me at all while I was around that level and BP.