It's all about making a significant change.
I have gotten my RNG to change by messing with mods before to make sure K2's Daze landed.
So there are several things that can be changed to alter the RNG of future turns:
Members of your team
positions of your team
attack order
which abilities are used.
equipped mods
Sometimes who the enemy is attacking is based on the spot they occupy, sometimes it is based on who they are. For example: on Node 9 QGJ may attack my Jawa Engineer because of his low health and will still do it after I move him. But Kylo Ren was attacking him the first order and not the second since it is the position he was attacking and not the character
Altering mods to change up speed, crit, tenacity, or potency with your mods can be enough to change RNG. Speed could change the turn order. Crit could change the damage dealt. Potency and Tenacity can alter whether or not debuffs will land. Any of these feats should be enough to change RNG.
If I know attacking Dooku will result in him resisting my K2's Daze, I can either attack someone else, or use his basic attack to daze him on K2's second turn.
I've even had something as simple as dropping one of Jawa Engineer's thermal detonators on someone different give me different RNG (the detonator never exploded in either situation).
The point is not just changing up what you do, but doing it enough to alter what occurs as a result of your actions.
I would say that it sounds more like you are too dead set on using certain abilities as opposed to not changing up your members enough.