>>96061519
I wouldn't say OP, but CIS is by far the most forgiving faction for a new-ish player to pilot, and one of the hardest to play against as a new player.
With their coordinate keyword they usually get great order control, they are less susceptible to suppression, and a lot of their units are very tanky for their points (B2s, BXs, Magnas, Droidekas, Aqua droids, AAT, Snail tank and Crabs are all pretty tough)
As a Rebel player their are some ways to deal with them
>MPL-57 Rebel Troopers and M-45+Rocket Landspeeders
Ion will fuck up droids really hard, and Impact helps with the armor.
>AT-RT with Laser cannon
They are a cheap source of Impact to deal with armor, and good range can usually keep them out of trouble
>Sleeper Cells or Fleet Troopers
Big dice pools will get through any defense
>melee units
That can mean Tauntauns, Wookiees. Fleet troopers or a hero like Luke, Ahsoka or Din Djarin. These will usually make short work of Droidekas.
Part of it also depends on your opponent's list. It's important to focus on their hard hitting units when possible.