Unlock Devil Kazuya:
Devil Kazuya cannot be selected from the 'Character' select screen. Devil Kazuya is unlocked by selecting Kazuya Mishmia and performing an in-battle transformation with one of the following methods.
Kazuya can transform into Devil by using his Rage Moves. If performing the Rage Art when you get to low health press RB so he executes a string of moves where Kazuya transforms into Devil temporarily, if however the opponent is still standing afterwards (or the attack is blocked), then Kazuya will remain as Devil for the rest of the round and gain some additional attack properties. Note: He won't remain as Devil between rounds.
Kazuya can also transform into Devil by sacrificing his Rage to transform into Devil directly, rather than using his Rage Art.
Violet is the only in-game clone character and he can be selected from the 'Character' select screen by picking Lee Chaolan and his Player 2 outfit before a match. Press X or B to get his costume. Note: It's merely a skin/palette swap.
When you buy the Tekken 7 Season Pass (which also comes included with the Tekken 7 Deluxe Edition) you will be granted access to ALL additional DLC fighters as they get released over the coming year. It has been confirmed that 2 new guest characters will be added to the roster through the Season Pass, namely: Guest Character #1 arrives in Winter 2017 and Guest Character #2 arrives in Spring 2018.