Well, I don't think we would be having this discussion if not for Dengaroo winning Worlds, but whatever I guess.
What is in my opinion the most broken, if you will, thing about Zuckuss is his price. For only a single point you get an ability that can be used any number of times per turn for basically free and after your opponent rolls his defense dice. Now looking at the other Scum thing that re-rolls defense dice, R4-B11, he has a 3 point price AND needs a TL to work.
In my opinion Zuckuss would either need to be many more points, like 5 or even 6-7 or have more restrictions, like a TL on the target which also indirectly hits Manaroo's ability since you will need to be close so you can TL + focus Dengar if you want to use Zuckuss. Another thing you could do with Zuckuss could be to have his ability mandatory to activate for all defense dice. So basically if you chose to use Zuckuss, your opponent would re-roll all his dice, not just the ones you want.
At 5 points you've got a card that is still going fit into a Dengaroo build (with a few less toys for Manaroo and a smaller initiative bid) but end up with a card that is ridiculously overpriced to use on any other ship.