when you hit 85 farm 10th division as much as possible and upgrade your lvl 80 gears, also improve your hp as well since the 30th floor will pretty much abuse you for a while till you do thanks to the triple support attacks. That hp will also be useful for doing the 5v5 fights against the espada's
You will struggle to do it until you got very good defense and carrying a BP of about 500k (give or take a little) in all likelyhood in order to complete all 3 of the 5vs5.
And that has to be a balanced team 500k, not a "lets just boost my main" one.
They deal out huge dmg and take very little. And my god you need a lot of hit (Eagle eye raider title helps in 1v1's)
I really should have a look at the 2nd fight again, just is rather horrible seeing myself getting slaughtered last time