Throughout the game, you can unlock transformations. There are some used by all and some that are race only. Some of the transformations are unlocked by using a certain race.
Unlockable – How to Unlock
Future Super Saiyan: Complete the last story mission after the credits with any character.
Kaioken: Complete the Ultimate Finish in Parallel Quest 8 Invade Earth with any character.
Turn Golden: Complete Frieza’s Spaceship Quest 18 The Omnipotent Frieza. Then talk to Cooler and Frieza once. Complete the next quest. Frieza race only.