The worst problem for Luke would be getting into the ship itself. I'm going to err on the side of optimism and believe that Luke Skywalker could jump or do something to get him into Sovereign and then it's just a simple final level (ala Death Star) with Luke being completely immune to indoctrination. Platforms, minions, all on the way to some weak-point inside Sovereign probably with a boss defending it. I find myself tempted to vote Luke Skywalker, but I think it's more because he's the hero and you'd expect him to win in a situation like this. So I'm going to say it's too close to call, it'd be awesome tho.