I just finished the game for the second time. Earning the last achievement :)

In the final battle I used:
Rian with abilities fleet shot 2 and aimed shot 3, spot weakness 3, sharp sense (tracker / grave dancer)

Alaydon: motivating chord 3, grand concert 3 (songteller for the necessary healing)

Breg: Sharp sense, Aimed shot 3, fleetshot 2 (tracker)

Hup: call pet 3, command 3, lend a hand (tamer/ paladin)

Brea: inspiring presence 3, dreamfast, cleanse 3 (strategist/mender)

The final battle is pretty tough, but maybe the one where you have to free tavra and seladon is the hardest, because they are weak and the mission fails when they die.....

however the final battle against the emperor (and 2 more skeksis) you need a healer, somebody who can cleanse and you want to be poison resistant to make life a lot easier.

The way I configured my skills enabled me to do over 2000 dmg in a single turn at time, because of the mark effect ot the spot weakness skill, combined with act again and Aimed shot 3. So first attack from a distance with fleetshot 2, thus marking the target because of spot weakness. Then with some luck you may act again and can immediately throw aimed shot right after.

Then the next character can use a skill that requires the target to be marked, because aimed shot 3 does not consume the mark.

Or you can just use motivating chord 3 on Rian in my case to throw aimed shot 3 a second time in 1 round. Thus pushing the dmg over 2000 :)

The final battle recommands level 90, but 88 was sufficient for me.

I guess I could have swapped Brea's shockwave 2 for something more useful, but in the end, my team had enough speed and power.