This is an idea I was toying with based on some of the threads that have popped up recently that propose banning certain cards. I am not in favour of such a move as which cards to ban is going to be pretty subjective.
As an alternative, I wondered how it would affect the game if all cards were made unique. You could still have a Deadeye/U-boat but only 1 in your list. It seems to me that this would reduce spam lists which can be boring to play against without unfairly penalising any particular pilot or faction.
You could apply the Unique rule just to pilots or you could apply it to upgrade cards if you really feel like it. What effects would it have on the meta? My hunch is that it would not affect Rebels too much as most competitive rebel lists tend to revolve around named pilots anyway. Restricting IA could be a little harsh if you want to field more than one X-Wing perhaps.
Scum would lose out on U-boats but Dengaroo and others would not be overly affected. My friend runs a Scyk swarm to be contrary but he just likes to prove a point.
Imperials might be a little more affected. Tie Swarms would become a bit trickier as you could not spam Academy Pilots and would need to cope with slightly fewer ships and differing PS values. Also Ace-wing would need to decide who gets the Autothrusters. This might see more varied Ace lists with Vader and Defenders featuring more.
Obviously this is only intended for "house rules" but it strikes me as interesting way to mix up the meta a bit without obviously targeting any single build, card or faction.