First to have an undefeated team you need to go to gamemodes then multi-season. Choose a team and go into roster on the side bar. When you go into roster you can trade players and you can get the best players all on one team. With every really good player from each team it will be really hard to defeat.
When attempting an alley oop, make sure there is someone running to the basket. You have to make sure you're passing it to them though, and also make sure it doesn't get deflected. SO How to actually throw the alley oop: you have to take your hands off of the joystick. Don't touch the joystick (the controller to move players). Then just click the alley oop button. You can't throw the alley oop when your still moving the player. It won't work all the time, and it's easiest done when you've stolen the ball most of the players are running to the court. Enjoy! Lala
More often than not when you try to strip the ball the questionable responsiveness of the controls will lead to more fouls than steals so a good strategy is to just let the AI on your team handle the defense.