FIFA Soccer 06 Cheats

First of all you must be in manager mode, (this cannot be done in a match), save the game then quit off of manager mode, load it up again and your players stamina will be almost fully refilled
You may do this as many times as you wish to make your team's stamina full

If you go to the Team Squads menu, and put the worst possible starting eleven in as the first eleven, you will be able to select that team in manager mode as they will no longer be rated as 5-stars. You then save your Manager Mode game, go back to the squads menu, put the original eleven back in and load up your Manager Mode game once again.