@Empiric1
You have a got a viable PVP-Team. Use your strongest chars in arena unless synergies are better than a single char. Could you perhaps give some more deatailed information about stars and gear? To me it sounds a bit like a beginner PVP-Team of a P2P (hello Aayla) around lvl 60+(as i was running a similiar team for a very long time with Phasma/Sid/Lumi). Sidious is ok in Arena, even though he is better as a leader in PVP (as you said - he is not a great DD on his own). Phasma teams can be annoying - but your team has no real Phasma synergies right now. If you want go with her Kylo Ren is worth farming. Do it. I dont have or need Kylo, but he is viable. Current meta is all about speed and damage (Phasma is a bit too slow right now, but still competitive). Luke Skywalker is just ok - due to the fact you already run Poggle you should concentrate on farming Geonosian Soldier in Cantina/IG86 in GW. Geo is a beast, has great synergies with Poggle, and also fits in every PVP-Team - all in all is better than Luke (like Luke 2.0). IG86 is also strong (Droids/Poggle/GW). Boba Fett - well, he is ok, good for your tank challenges...ok he can revive himself and ability block once - but does no damage in PVP. Poe and Fives are better to my mind (also Royal Guard for P2W). HK47 is ok (Droid Team/Poggle synergy) as kind of a little Old Ben. Good to have, ok in Arena, but no must have. Or do you try to build a Droid Team (HK/IGs/Poggle...)? Daka is always worth investing in - she is a beast defensively wise if not killed first. You should invest in her in the long term. Also helping you a lot in dark side missions (or borrow her).
Forget about Ashoka/Talia (only as much as needed for dark side/light side missions. Aayla is great - but only with lots of stars. Generally said: do not invest too much in chars you won´t get 7* soon (Aayla/Darth Vader). Ackbar - hhm, is ok in Galactic War for healing (vs Sid/Darth Vader/Phasma,...but unfortunately thats it in GW) or in a full PVP Rebell Squad (at least as leader + Han Solo)...otherwise forget about him. No damage. If i were u i would invest in QGJ before Daka. Farming Kylo shards(how many Stars?) if you wanna run Phasma or Sid as leader, otherwise farm Geonosian Soldier soon. To my mind QGJ and Geo are the best toons in this game right now.