I want to buy, one core box and 2 extra units one for rebellion part one for imperial part. which ones should I get to make the game equal for both sides.
or should I go like, 2 core box 1 t 47 and 1 at-st?

thank you !

To make a legal list, you’ll need at least 1 extra trooper unit per faction.

So either 2 core (you will be missing some upgrade cards, but for a bit more you will get a lot of options) or 1 core and 1 of each trooper for both factions.

That should give you all you need to start. From there, get whatever you would like.