For evasion feat,
1. GL Rey grants mastery when an enemy gains TM.
2. Rey (Jedi Training) gains evasion percentage when her mastery increases
3. Ewoks gain TM like crazy
4. Ewoks use lots of assists to make lots of attacks
Answer? Use your GL Rey + JTR + 2 toons that deal no damage + R2.
Rey uses nothing but Lifeblood
R2 stealths everyone but JTR over and over
HY or Barriss or whoever heals damage Rey takes when using Lifeblood
BB-8 or whoever just does their no-damage thing.
Use cooldown reduction disks so that R2 never has to use a damaging ability. Use HoT data disks if you don't have a healer (or if you don't have enough auto-buff disks to keep the Cooldown Reduction train going). But try not to use HoTs if you have a healer and don't have Rey's ultimate because you'll need to take enough damage using lifeblood that you will charge up Whirlwind. If you don't have the ultimate but are using a healer like Barriss, remember to let her hit the ewoks a couple times at the beginning while Rey gets a whirlwind charge. Once it's charged, just keep using heal abilities. Luminara is particularly good for this as she grants HoTs which help to activate the Cooldown Reduction disks.)
For JTR, just use her basic. It won't deal more damage than they can regain through protection recovery from Wicket or whatever.
Pretty soon the Ewoks are using mass assists & missing every time. Unfortunately you can't put it on auto b/c the AI will have JTR use mind tricks and the Ewoks will stop gaining TM%. But other than having to play manually, it's perfect. You can easily get more than 100 evades in a single battle and still win using Rey's Ult (if you have it) or just going all out for damage right at the end if you don't.