I think for these assault battles challenge tiers a few exceptions should be made due to some of the newer squads having leaders that don't fit the faction for the rest of the team that they normally lead that people have developed. The key examples.
Shaak Ti and General Skywalker generally lead Clone Trooper squads, yet neither can be used in Military Might which usually has a clones or rebels requirement, because they themselves are not clones. That makes Clone Troopers probably unable to complete the challenge tiers of the events because their best leaders are ineligible to run the event. The simplest way to deal with this would be to change the clone trooper requirement to Galactic Republic requirement I suppose that'd also make Padme led jedi and droid teams eligible so maybe just allowing General Skywalker and Shaak Ti herself. For up to mythic tier the current requirements are fine just use Rex but I don't know if Rex leads can do Military Might challenge tiers.
In Ground War, the factions are Jedi, Ewok, and Ugnaught (why Ugnaught?). That basically means Bastila or Jedi Knight Revan teams because the other common Jedi team leader right now, is Padme, but she is ineligible for this event because she is not herself a Jedi, even though it's very common to run Padme with at least 3 Jedi, and a 4th like Barris, Shaak Ti, or Grand Master Yoda is fairly common as well. She's the best Jedi Leader I have, and I have her developed well, but I can't use her (not in any assault battles actually)