First, let me guide you to this wonderful thread created by @Sammy, where
yet another Databook was proven false -
Sabo Is Alive - Oda Did Not Confirm Sabo Is Dead!
Misconceptions about Databooks
The databooks are
not written by Oda, it does not contain facts that "Oda" has confirmed,
it does contain information at times not revealed in the manga such as character names etc but most of the content in Databooks
are put together based on knowledge from the series -- it's like a guide to One Piece, all knowledge of One Piece (mainly related to characters) are gathered in this book.
Databooks often are quoted to have "confirmed" something which only turns out wrong later, it is because they are just data we already know simplified or wrapped up for the sake of simplification. Fans should by now know not to trust the Databook's words 100% -- the Databooks are unreliable at the best of times.
But, if the Databook is put together based on knowledge from the series, then it states Zoro is equal to Luffy!
Wrong! The Databook
never stated Zoro is "equal" to Luffy, the databook only
contains a table of character traits, and the "strength" trait had numbers 1 to 6, 1 being the weakest and 6 being the strongest. Both Luffy & Zoro had "6/6" on their strength trait.
The Databook containing this "traits"
was published in 2002/2007 (Red and/or Yellow Databooks), the information stated in that is quite dated now (especially post timeskip). No where is it stated that Zoro & Luffy are equals, "strength" in One Piece is very basic, as "strength" isn't all that counts while two opponents face each other, if "strength" was the most important trait in One Piece, then Giants would be the strongest race (whereas we've seen that isn't the case.)
But the Databook states in written words that Zoro is equal to Luffy!
Wrong again! There is no "translation" of the whole Databook, neither did any
reputable and credible fan translator complete the "translation." There exists many "rumors" and "false" translations of what the book states:
CCC from Arlong Park Forums who is a credible and respected translator has stated:
"He can stand shoulder-to-shoulder with Luffy when it comes to combat ability"
It's still ambiguous language. It definitely doesn't say "he is just as strong as Luffy." Just that he's up there. Really strong.
That is the language used, and as CCC confirmed
it definitely doesn't say "he is just as strong as Luffy."
Hopefully this clears out any and all doubts about this debate, it is not confirmed anywhere (by Oda or Databooks) that Zoro = Luffy.