How high should I take my Phoenix squad?(EP/Thrawn)

Fwiw , your attackers should be geared higher over the tanks, they are the ones that need to be doing the killings lol, g9 for sure, for all even better, with decent mods , and you should be ok. However, the big thing is the omega uniques, The shared uniques is what makes Phoenix work so well. Without having them maxed out, you will be needing either higher gear levels, ie 9plus, or better/faster mods,