P1 - Theoretically - 10 JTREY maxed teams can do phase 1. But everyone wielding them would have to gear them to max(or close), mod them with very good speed and damage, and - most importantly - restart the fight until they do those 10%. Because it requires some really good rng and decisions.
I did 10,5% once so I know how well modded and geared and how good rng you need... 5+% is matter of max 3 tries, 7+% may be 10 tries and 10+% ... rng decides how soon you manage that.
P2 - I have trouble there too, saving deathmark for p3, but what can do 1% (approx 500 k) or nearly that:
Thrawn lead remaining troopers
Team around Sabine & damage dealer (e.g. GK, Zariss, Sabine, Wampa + 1)
Nute lead with Leia + 3 defensive toons (tanks/healers)
P3 is chexmix
P4 if you do a lot of retries/gearing/zetaing/.., you can get very good dmg with nightsisters and breeze through DN with only 5 teams ov ventress lead NS !..
Sion and traya are then doable with remaining sink teams.
So lots of coordination, focus and skill and it will be doable. Key point is ofc utilizing those 15 JTREYs you have, those guys must think only about maxing team around her till they bloody do their 10%.