UPDATE!!!!
Not only i managed to get number 8's mission score, BUT I S-RANKED IT!!!!
The thing that i changed this time around was removing the ability Combo Master.
I'm not sure if that really was the problem, but it would make sense since Combo Master makes you ignore the enemy's state and keep hitting (likely why i kept bouncing away with master)
Anywho, here's the stuff i had equiped when i got it:
- Critical Mode Lv99 (just posting for the curious)
- Keyblades
Ultima Weapon (Main hand) (MP Hastega)
Fatal Crest (Master Form) (Berserk Charge)
- Abilities (that matter)
Berserk Charge (if you're equiping Fatal Crest i guess it doesn't matter)
2 Form Boosts (I was using Master Form for this so i guess it matters knowing that i had all the time in the world)
MP Haste
MP Hastera
No Experience (i got every level gauge maxed out, no reason to keep it OFF)
Total MP Acceleration count: 150% (Ultima + Haste ability + Hastera ability) (no full blooms equiped)
Method:
Master Form, cast Curaga, start it, Lock-On, keep attacking (don't mash it, just press at a medium/fast pace) when you get your MP back cast Thunder (SHORTCUT IT!!!!!) until you're out again, if you're lucky you might be able to fit in a few more hits and get to 85 (or 99 if you're going for the S-rank)