Well I made a blog of Smoker and Garp's similarities before, this one is for Rayleigh and Zoro.
Here are the one's I could think of:
1. Both are swordman, Zoro is a more hardcore though.
2. Both are the second man of the crew, well Rayleigh was official where as Zoro is not, but we all can see it.
3. Both have some weird problem, for Zoro, it is his horrible sense of direction. For Dark King, it is his weird luck with ship wrecks, you know he was ship wrecked at least twice. Once Hatchan saved him and the other time he swam to Amazon Lily.
4. Both are in the crews of the Late and future Pirate Kings respectively.
Tell me if you can think of any more and by the way can anybody tell me how to add a voting list with a blog?