Killer Instinct Gold Play as Gargos: Press ZARZAB.

All Options:
Z, B, A, Left Shift, A, Z.

(In the options menu)

Play in the Sky:
(2 player mode at select player screen)
hold down the analog joystick.
Press the bottom C button) simultaneously.

Multi-colored Players:
(At character select screen)
Press ZBAZAL