In Batman and Robin #4 (of the New 52) Batman makes this remark to his son:
Who are the six people (including Ducard) that trained Batman?
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The list of people who have trained young Bruce Wayne before he became Batman, IN THE NEW 52, has changed from version to version as DC Comics have revised the character's history, there is a really good story called The Many Deaths of the Batman that shows a killer taking out Batman's trainers but it has been long since dropped from continuity. I only have a partial answer for this question though.
In DC's The New 52, in Batman and Robin #4 we learn that Bruce Wayne was trained by six mentors and that Henri Ducard was the last of these mentors.
In the Batman and Robin title he also says he trained with two mentors whose names were Chu Chin Li and Tsunetomo.
In the New 52 Detective Comics Annual 2012 we see a young Bruce Wayne training with a master named Shihan Matsuda.
Now we know that young Bruce Wayne must have trained with Ra's Al Ghul and met his daughter Talia and at around the same time unknowingly fathered Damian Wayne with Talia, so it's possible that Ra's Al Ghul is himself the fifth mentor but this is as yet to be confirmed at least to my knowledge.
This leaves only one unidentified mentor of the six.
The DCnU has not released who the other five trainers of the Batman have been since they rebooted their universe. Only Henri Ducard has been revealed to have trained the Batman since the reboot. It is unlikely, DC will ever reveal the names of the others, so writers can alter the history to their needs.
DC Comics has always maintained a level of anonymity around the number of people who have been involved in the “training years” of Bruce Wayne before he became the Batman. Even now, naming six only means these are the ones Batman will admit to.
One of the many lists indicated quoted from the Many Deaths of the Batman included: “All four were experts in their fields: a race car driver, a demolitionist, a chemist, and a body builder. A fifth turned up, a gymnast.” This list is likely far from complete considering the many skills Bruce Wayne has displayed over the decades.
In previous continuities (Pre-Crisis and Post-Crisis):
Ted Grant a.k.a. Wildcat of the Justice Society was one of the heroes who mentored and trained Bruce Wayne in fighting techniques, particularly in boxing. He likely also trained Wayne in effective fitness methods and crime-fighting techniques.
Giovanni "John" Zatara: Stage magician and secretly a member of Homo Sapiens Magi, a subgroup of magically adept humans. A powerful sorcerer, he is perhaps best known for being among those who trained Bruce Wayne in a process that would eventually lead him into becoming Batman.
Henri Ducard: appeared in “Blind Justice” (Detective#598-600) introducing Ducard and Tsunetomo also appears later in Detective Annual #3. Ducard was an excellent, if amoral, detective particularly skilled in man-hunting. He teaches the uses of brutality, deception and cunning against the criminal element. His brutality causes Bruce to abandon him after a time.
Harvey Harris: “When Batman was Robin” (Detective Annual #1) - Bruce learns his detective skills from Harvey Harris, the best detective in Gotham. Batman disguises himself in a prototype Robin costume to hide his identity from Harris. Doesn’t help.
Kirigi: Batman #431 - Kirigi was a master of ninjutsu living in the Paektu-San Mountains of North Korea. A young Bruce Wayne had sought Kirigi for instruction, gaining some of the skills he would use as Batman. In that story it was also revealed that Kirigi has taught ninjutsu to several members of Ra's al Ghul's League of Assassins.
David Cain: one of the world's premier assassins, paid to eliminate some of the most famous and powerful people on the planet, no matter how impossible the task. He was one of the people who trained the young Bruce Wayne with the skills that he would use as Batman, although Bruce has, naturally, never used the murder techniques Cain demonstrated. He was also the father of the second Batgirl, Cassandra Cain. (Cassandra has been retconned out of existence in the new DCnU.)
Willie Doggett: “Shaman” (Legend of the Dark Knight #1-5) Alaskan hunter teaches Bruce tracking skills. Doggett is killed tracking Thomas Woodley.
Other continuity stories also mention a variety of training in Bruce’s early years.
The Man Who Falls: consists of a series of concentrated retellings of previously published Batman stories, including Detective Comics #33, which includes Gardner Fox and Bob Kane's first version of Batman's origin.
“Many Deaths of the Batman” (Batman #433-435) One of Batman’s teachers kills off others who trained Batman.
“Tao” (Legend of the Dark Knight #52-53) - focuses on Bruce’s training in the Far East.
Batman has also trained with the African Bushman (the Ghost Tribes of the Ten-Eyed Brotherhood, among others), traditional healing disciplines under Nepalese monks and even ventriloquism under skilled practitioners. --Batman: The Ultimate Guide to the Dark Knight, 2nd edition, 2005, DK Publishing (from my personal library)