@Vendi1983 Thrawn is necessary as you can use his fracture on Sion (against Sith) or Revan (against Jedi).
You should cut through JKR like butter...once you get C3PO that is. My CLS team often doesn't lose a character against JKR and sometimes wins without even taking damage.
Personally I mod CLS with a potency cross and offense triangle. Potency ensures that buff immunity will stick on GK (the "easy button" for CLS against JKR). You could go with Crit Dmg triangle too, just use whichever has better speed.
You definitely want CLS as your fastest, followed by R2.