Hold L1 + L2 + R1 + R2 on any non-Story mode character select screen, and press the following to unlock the specific character

Arii

X, SQUARE, TRIANGLE, CIRCLE, SQUARE

Carla

X, SQUARE, X, X, X

Chukklez

SQUARE, SQUARE, TRIANGLE, X, CIRCLE

Cruz

CIRCLE, TRIANGLE, X, X, CIRCLE

D-Mob

SQUARE, TRIANGLE, CIRCLE, X, CIRCLE

Dan G

X, CIRCLE, X, CIRCLE, SQUARE

Deebo

CIRCLE, CIRCLE, X, X, TRIANGLE

Deja

CIRCLE, SQUARE, CIRCLE, CIRCLE, X

DMX

CIRCLE, X, CIRCLE, TRIANGLE, SQUARE

Drake

TRIANGLE, SQUARE, CIRCLE, X, X

Funkmaster Flex

CIRCLE, TRIANGLE, CIRCLE, CIRCLE, SQUARE

Headache

TRIANGLE, TRIANGLE, TRIANGLE, SQUARE, CIRCLE

House

TRIANGLE, X, TRIANGLE, CIRCLE, X

Iceberg

SQUARE, TRIANGLE, CIRCLE, SQUARE, CIRCLE

Ludacris

CIRCLE, CIRCLE, CIRCLE, SQUARE, TRIANGLE

Masa

X, CIRCLE, TRIANGLE, SQUARE, SQUARE

Method Man

SQUARE, CIRCLE, X, TRIANGLE, CIRCLE

Moses

TRIANGLE, TRIANGLE, SQUARE, SQUARE, X

N.CIRCLE.R.E.

CIRCLE, SQUARE, TRIANGLE, X, CIRCLE

Nyne

SQUARE, CIRCLE, X, X, TRIANGLE

Omar

CIRCLE, CIRCLE, SQUARE, TRIANGLE, TRIANGLE

Opal

CIRCLE, CIRCLE, SQUARE, SQUARE, TRIANGLE

Peewee

X, X, SQUARE, TRIANGLE, SQUARE

Penny

X, X, X, TRIANGLE, CIRCLE

Pockets

TRIANGLE, SQUARE, CIRCLE, SQUARE, X

Razor

TRIANGLE, SQUARE, TRIANGLE, CIRCLE, X

Redman

CIRCLE, CIRCLE, TRIANGLE, SQUARE, X

Ruffneck

X, SQUARE, X, TRIANGLE, CIRCLE

Scarface

CIRCLE, SQUARE, X, TRIANGLE, SQUARE

Sketch

TRIANGLE, TRIANGLE, CIRCLE, SQUARE, X

Snowman

TRIANGLE, TRIANGLE, X, X, CIRCLE

Steel

X, TRIANGLE, CIRCLE, CIRCLE, TRIANGLE

T'ai

CIRCLE, CIRCLE, SQUARE, X, CIRCLE

Zaheer

TRIANGLE, TRIANGLE, SQUARE, X, X

Alternate Costumes