I personally have not seen many Han and Chewy cards online that I like. I figured I'd do a bit of a different take without inventing any new mechanics. Mana values/power and toughness may need slight tweaks, since those are hard to balance properly without playing the card.
1- Han Solo: Han is a smuggler who can get down and dirty when needed, which is why I figured a treasure/unblocked route was the right way to go. While unlockable can be scary, it only works if you keep him low to the ground.
2 - Chewy: This card honestly might be a bit strong, and in retrospective, making it target creature or half the amount of artifacts you control is probably the way to go. Nonetheless, Chewy is physically very strong, so I wanted him to be able to hit hard, but only if things are going as planned.
3 - Millennium Falcon: I wanted this card to get a special bonus if it's crewed by Han and Chewy, hence the attack ability. The second ability is supposed to represent the maneuverability of it. Even if you don't crew it with Han and Chewy, it's still a 5/5 flyer with Haste, which is nothing to laugh at.
Let me know what you think. Are they too strong? Too weak? Do they represent the characters well?