Pause the game then do whatever code you want 

99 Lives:
R2,L2,R2,L2,up(4x),circle 

PaperSpyro:
right,left,right,left,L1,R1,L1,R1,square,circle 

Big Head Spyro:
up,R1,up,R1,up,R1,circle(4x) 

Squid Skateboard:
up(2x),left(2x),right(2x),down(2x),square,circle,
square 

Easy Mode:
circle,square,right,left,right, square,circle,X 

Hard Mode:
Same code as easy mode but instead of that last X,
press Square.