What fighting style does Tim Drake use?
Well, I imagine he has a mix of lots of things. He was trained by Batman who is a master of ten million forms of martial arts and improvises with all of them in combat. When he first officially earned the mantle of Robin, he went to Paris to train with an exiled last living teacher of an obscure form of Tibetan martial arts. Then during the One Year Later story line, he spent a year abroad with Bruce and Dick further training himself. When he came back, I’d say his skills got a major upgrade since he went from running from many fights to being able to take down a bunch of League of Assassins folks all by himself. If you are really interested, you might read those One Year Later comic books to see if it mentions any specific training.
I wouldn’t be surprised if other styles were mentioned in other books, but that’s the best I can do.
Googling obscure Tibetian martial arts, I found this which isn’t particularly impressive. https://www.facebook.com/chogyal.rinpoche/videos/1853618591586889/