Given that the emperor uses ones aggression to lure them to the dark side:

Darth Sidious- When an enemy ship within your firing arc causes you damage, that ship receives a stress token.

4 pt crew card. Imperial only. Reword as need.

That's very similar to a Rebel Captive! Surely the Emperor is more fearsome than Bob the Rebel Accountant who got arrested last week?

I like the already mentioned boost to pilot skill. "Non-Unique friendly ships within range 1-3 gain +3 to pilot skill" or something to that effect.. +3 because the pair of Royal Guard pilots escorting him would be on their A-Game and PS-9

This happened in TIE Fighter.

I don't see why not. But only if we can also get Mon Mothma.

When an allied ship range 1-2 misses an attack roll it gains a focus token. Allied ships within range 1-2 may retain 1 focus token during the clean up phase.

He focuses his forces and empowers them.

I'd probably want to see Palpatine as something like "At the start of the combat phase, increase the pilot skill of all friendly ships by 1." Would allow a VI Vader or Soontir to fire at the same PS12 as someone boosted by Roark.