Varied Martial Arts depicted in TekkenMishima-Ryu Karate - Kazuya Mishima, Heihachi Mishima, Jin Kazama (T3 & TTT, being a variation of Mishima-Ryu Karate and Kazama-Ryu Kobujutsu)
Based on: Kyokushin Karate, Goju-Ryu Karate, Shotokan Karate
While Mishima-Ryu is based off of numerous styles of Okinawa Karate, Mishima-Ryu is most heavily based on Kyokushin Karate. For more information on Kyokushin Karate, Jin's style of Karate is Kyokushinkai.
Kazama-Ryu Kobujutsu - Jun Kazama, Asuka Kazama, Jin Kazama (T3 & TTT, being a variation of Mishima-Ryu Karate and Kazama-Ryu Kobujutsu)
Based on: Aikido, Aiki-Jujitsu
While Kobujutsu generally refers to any ancient Japanese Martial Art, Kazama-Ryu heavily depicts the use of Aikido and Aiki-Jujitsu, along with numerous strikes, where as Aikido and Aiki-Jujitsu is mostly Grappling Defense
Sumo - Ganryu
The Sumo shown in Tekken depicts Ganryu the ability to perform attacks via sitting down, where as in real Sumo that Sumo Wrestlers are forbidden to touch the floor excluding their feet
Capoeira - Eddy Gordo, Christie Montiero, Tiger Jackson
The Capoeira shown in Tekken uses both Capoeira and Gymnastics, as well as breakdancing (such as the Flare and Windmill move)
Vale Tudo - Craig Marduk
Based on: Mixed Martial Arts, Professional Wrestling
While Vale Tudo/Mixed Martial Arts can be generally any style the practitioner is comfortable with, a lot of Marduk's moves are over-the-top power moves and are based on Professional Wrestling as well (Jack-Hammer), seeing that Professional Wrestling would usually never be depicted in a MMA match (for more info on Mixed Martial Arts and Vale Tudo, watch UFC and PRIDE Fighting Champions). (Thanks to Icege for correcting an error in MMA)
Hakke-Ken, Hike-Ken and various forms of Chinese styles based on Hakkyoku-Ken - Ling Xiaoyu, Miharu Hirano
Based on: Wushu, Hakkyoku-Ken/Baji Quan
While most of Xiaoyu's (as well as Miharu's) moves are actually based on Wushu, which happens to be a sport of Kung Fu in China, she weilds some knowledge of Baji Quan.
Chang-Ryu Kenpo and various forms of Kung Fu (Xing Yi Quan) - Michelle Chang, Julia Chang
Based on: Chang-Ryu Kenpo, Xing Yi Quan
Xing Yi Quan is one of the three major internal Chinese martial arts (the other two being Tai Chi Chuan and Ba Gua Zhang) and is characterised by aggressive, seemingly linear movements and explosive power. They seem to be derived from the techniques of the spear wherein the body moves as a unit and created an explosive force. (Thanks to T5 Jin for the info)
Julia and Michelle use the combination arts of both Xing Yi Quan and their own personal style on Kenpo.
Kickboxing - Bryan Fury
While Bryan holds moves that are very authentic to real Kickboxing, he also holds his own type of moves and Professional Wrestling throws.
(will add more later)