The numbers refer to Attack 1, Attack 2, Attack 3, and Attack 4.

The MK team began using this system in Deadly Alliance. They also used it in Deception, Armageddon, and MKvsDCU.

On PS2/PS3:

Attack 1 = Square
Attack 2 = Triangle
Attack 3 = X
Attack 4 = Cirgle


Xbox/Xbox 360:

Attack 1 = X
Attack 2 = Y
Attack 3 = A
Attack 4 = B

Wrong forum, question answered.

Thread closed.