Advice for a returning player

I currently have 90/145 shards for GK, as I haven't been in this guild simming HAAT for so long, but I should have him unlocked in a couple of weeks. How does he fit in this suggested gearing list? He'll be 5* initially, so not that useful, but I know he's important in this squad. Mace (his substitute) just doesn't cut it.

I would use Fives as the substitute, not Mace. (Padmé, JKA, Ahsoka, + GMY & Fives, the last two of whom will be rotated out when possible, but are just fine for now)

As for GK's fit in the gear priorities, I would just post again here so I can see where you're at with the rest of them before I give any advice on that. Priorites can change with new situations, and you definitely want GK to move up quickly. From g7 to g9 he uses a LOT of carbantis & Mk5 Stun guns, but once you hit g10+0 you're almost done with Carbantis and completely done with Mk5 Stun Guns (at least until g12+3, some of that right-hand g12 gear will use carbantis or stun guns as a component and I didn't check that).

The upshot of that is that you can't just take him up to a useful gear level like g9 and then leave him there for a while, like you would if all his StunGun needs and most of his Carbanti needs were above g9+3.

Because of this distribution, you're either going to leave him at g7+4 or you're going straight up to g11+5, one or the other. His gear list just doesn't allow for much middle ground.

And he's important to this squad even before he becomes as tanky as he later gets because he has that AoE cleanse + retribution - and the enemy really doesn't want you to get retribution on JKA. So I'll look at how your Fleet is coming together & whether you're moving up ranks & such (which would indicate that maybe we can put off adding gear to Ackbar and/or Tarkin) at that point, plus generally assess how much progress you've been able to make in the next 2.5 to 3 weeks and that will give me a better feel for how soon you really need GK done and how much it will hold you back to leave other toons undone. Then I can make a recommendation from there.

The only other imperials that I have that could potentially be but in there are Royal Guard and Snowtrooper (got a lot of their shards from Bronziums) and Magmatrooper, but Bastilla is probably better than either of them. I also have all the shards I need for Savage, is it worth it gearing him?

As I remember, Snow is light on the Stun Gun requirement. Let me check that.

Yep, Snow requires no Stun Guns through g11+5. Magma is the same. I think bringing Magma or Snow up to g9+0 would be a useful intermediate step that would help the squad some without sacrificing too much necessary gear. That would require only 50 carbantis for Magma, +100 Stun Cuffs which can be had for Guild Tokens. Any Carbantis spent are sad, but still you can get to g9 without too much sacrifice.

Snow is about the same, but needs 50 fewer Stun Cuffs (and needs the Carbantis at g8 instead of at g7, but the number is still the same).

If I were you, I'd put in a g9 Snow or Magma until you can get Bastila (Fallen) up to 5*/g9 or better.

Also, when you put Bastila (Fallen) in, make sure you give her the best speed mods you can get outside of your Arena team. There are different ways to mod B(F) that are all valid, but when she's weak enough that she might be taken out before she gets a turn, you need to speed her up so that she gets that turn. One good AoE debuff from Bastila is worth a LOT of TM to the rest of the squad when running Palp lead.

I have all R2 shards. I'll level him up to the level you mention, as well as CLS after I've unlocked him, and probably forget a bit about him until I get Chewbacca and C3PO.

Exactly right. Or at least until you finish all the gear priorities you already have. He can still do some damage with your Princess Leia counterattacking from stealth vs. AoEs, and you'll get Han Solo long before Chewbacca. Although CLS really needs debuffers to get the most out of him, and he certainly needs zetas, if you've got your Arena squad up to 5x g12 then they won't be competing for gear with your up and coming squads.

So even before Chewie, if you have

5xg12 Arena
All zetas you intend to place on Arena toons done
5xg10 Empire/Sith Palp squad with g12 Vader
Palp zeta, Merciless Massacre zeta

Then if you don't have all the shards ready for your Bounty Hunters to go for Chewie, you can give some gear & zetas to CLS even though you don't have Chewie yet.

I assume you know that you're going for Bossk, Dengar & Jango for your Chewie event squad.

Okay, then. Good hunting. I hope to hear good news in a couple weeks!