to practice, start the rancor, turn off you phone's connection to the internet (airplane mode for me), then do whatever.
The droid team won't work, I'll be straight with you. Drop Poggle for HK-47 for sure. IG-86 or Chopper should replace Grevious and probably Phasma as well. Teams perform best with TMR, and droids have next to none. I advise not investing in this at all
the FO/Ewok team could, in theory, solo. Combining Teebo and Wicket gives 5 possible turns of stealth to go with that mighty 100% tmr on basic. When Teebo is called to assist that's the entire tm bar for the rancor as well.
But there are much better and more reliable teams. The first improvement I'd make is drop TFP for KRU and Krennic (KRU is both the better sub and the easier and faster farm) I could keep recommending improvements till you end up CLS, Jyn, Raid Han, Rex, Thrawn or whatever the record for beating Rancor is