Here are all the secret moves I know of

and by secret I mean that the game doesn't tell you that you can do them

Bycicle Kick: L2 + Triangle (hold)
Bow Kicks: L2 + Triangle + Triangle + Triangle
Front Jump: Double Press Square after hitting
Secret Grapple: backwards + Hold X and Square
Secret Grapple 2: while crouching, Hold Triangle + Circle
Slide: Sprint, press L3 then press L3 again
Spear Throw: R1+Triangle hold, then after hit press backwards
Sweep Kick: roll with circle then press Triangle
Football Kick: Hold Triangle when enemy down
Front Grapple: hit enemy with Triangle then press Square

Am I forgetting something?