Full ewok squad with one other (someone for tenacity down or speed down, or defense down preferably) is pretty slick especially phase iv.
Teebo (L), Rex, QGJ, Tusken Raider, and Dengar can solo it. 4/5 have tm removal on their basic attack. 3 have assists, 2 have buff wipes.Dengar can do speed down and tenacity down, plus has a chance to assist on his basic so could still potentially trigger tm removal on his turn. 60% chance to assist, 100% chance to call someone with tm removal on basic.
QGJ and Tusken Raider have 2 turn cd assists. they each have a 75% chance to call a tm removal on basic, of the 25% left, Dengar has a 60% chance to assist, which means they both actually have a 90% chance of calling in tm removal on their assists. Everyone has health steal and QGJ's assist heals the assister. SO no healer required, especially with the lack of Rancor turns. Rex also has a cleanse for debuffs, and Teebo giving stealth makes deathmark often ineffective.
If Teebo drops stealth, you can use his tm gain stealth ability to get it back, or use Rex's tm gain move, or just have everyone else do tm removal until his turn comes back around.
Rex has 100% chance for 25% tm removal. QGJ has 80% chance to remove 30%, Teebo has 100% chance (when stealthed) to remove 100%, Tusken Raider has 55% chance to remove 50%. All pretty high chance, high amount tm removals. If Jyn Erso is available, I would sub her for tusken raider as her potency stacks and stealing 100% of the Rancor's tm every other turn and giving it to herself works beautifully at keeping him down.
Other good subs include Chewbacca and Ewok Scout for consistency on tm removal (both have a 55% chance to remove 50% on basic) could be subbed for tusken raider, Rex, or QGJ. However, with their high percentage chances to remove, having those Rex and QGJ with Teebo is a high priority.
Tie Fighter Pilot is a good sub for Dengar as he has tenacity down. Fives can be a good sub with speed down on his basic. Luke can be a good sub with defense down and speed down on his special.
There's lots of comps that can be made out of the characters I have listed that can solo the Rancor, but Teebo, Rex, and QG are practically required... as is a tenacity down or speed down at the very least along with another tm reducer.
There's a priority in which debuffs to include. With multiple tm reducers the priority is:
Tenacity down
Speed down
Defense down
Offense Down
any other debuff
Also remember that debuffs on the Rancor are far better than buffs on your squad in general as the lack of turns he takes gives you numerous opportunities to land debuffs on basics and refresh cds on specials. Buffs however wear off sometimes like normal. Before I came to this conclusion I was looking at Kit Fisto for his potency up to make tm removal stick, but tenacity down is far better simply due to consistency.