You're just looking to beat the Defense Mods Challenge, right? In that case, definitely do not worry about giving a Zeta to QGJ; that's absolutely not necessary. Based on what you have, I'd go with QGJ, Old Ben, JC, Ezra and General Kenobi, once you get him up to Gear 7 at least. You should be working on that anyway. I did that challenge so long ago, I don't remember the minimum requirements, but I imagine Gear 7 should suffice.
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Old Ben
GM Yoda
Ezra
General Kenobi
Hopefully a Jedi rework is coming!