G12 Kylo Ren with Wat's tank tech (to get rid of healing immunity if it lands, but the little healing he gets from it is nice, too) is all you need to get silver box. That isn't red, of course, but it gets you the two Omicrons that are the real prize.
The other three should be basically anyone that will assist a lot to make that feat easier. Han and both Chewies is best, but anyone that assists will do. Use Kylo's AoE to keep up Retribution.
My ewoks are............. insufficient for this one ? But that's my fault. I always liked them and have been planning on working on them, but they keep being put on the backest of backburners.
