Get Any Player:
Enter the 'Lineup' menu and select a player to sell. Put him into the reserves by 
pressing B and selecting the 'Move To Reserves' option. Then, press R to enter 
the 'Comparisons' screen. Select the player you want to put into reserves, then 
press B and choose a player you want to buy. Then, press X to swap. When the 
swapping screen appears with the clock, try to get there football to go past the 0 in 
the middle. When they do so, move your football on top of theirs. You will now 
swap players and they will have to pay you.

Debug Menu:
Press R3 at the home screen and a debug menu should appear.