Someone that will help out your roster for sure (especially if you are looking to continue with dark side) is shoretrooper. It looks like you have him unlocked at 3* but not geared yet, which is fine. He is amazing at gear 9+ and 3*, trust me I have him 3* as well. He provides some starting protection from wiggs and other fast teams such as droids, as well as providing a great heal and crit immunity to all allies for a couple turns. It also looks like you have sun fac developed, so you could run some interesting double tank strategies.
As far as a dark side team for you (if you wish to do that), I would suggest the following:
Palpatine (L), Vader, TFP, Boba, Shore
Until you get shore up to par, you may want to run sun fac in there. You could also sub in sun fac for vader/TFP if you want to double tank.
It looks like you are developing Maul as well, are you planning on putting a zeta on him? I would be curious to know if you have access to those yet, and what your plans are for them.
If you wanted to continue with light side, then I would suggest developing a team around Rex. His leadership provides amazing versatility and works well against many different squads. The Rex/Stormtrooper Han (STHan) combo works quite well too, since when they crit STHan and he is taunting, you get fed a bunch of tm. Having a rex lead allows you to have a hybrid team as well, so you aren't chained to a certain faction, such as rebels. I would suggest the following "light side" (actually more of a hybrid) teams for you as well:
Rex (L), STHan, Boba, Biggs, Wedge
Rex (L), STHan, Boba, Palpatine, TFP
Rex (L), STHan, Boba, Sun Fac, Palpatine
As far as mods go for these squads, I would make rex the fastest, that way you can use squad discipline right away to get your STHan's taunt up asap. You would want you Boba fast as well, followed by biggs/tfp depending on which variation you run. The great part about having a rex lead, is you can switch it up based on who you are facing. For example: if you are facing a wiggs team, then you want palpatine/tfp. If you are facing a high dmg team or a team with lots of buffing going around and need the extra tank, then put sun fac in.
Another good thing about rex: he makes up for crappy speed secondaries on mods. This is something I struggle with as well. His leadership provides turn meter to fill what you lack in speed.
Something else I noticed in your roster is a great lack of speed arrows with the primary stat of speed. This is something you must fix immediately. My advice would be to check the mod shop at every reset and buy every single speed arrow you see. Refresh it with 15 crystals as well, since that isn't a bad deal. Buy only the mods that cost credits, however. If you can get a 5 dot speed arrow on each of your characters you will see your arena rank increase drastically no matter what team you run.