In infamous 2 after i beat my evil side will my good side be playable and if so how?

After you beat the game a second time, all powers become available for purchase, regardless of karma. If you beat the game on hard, then that ending is locked in. On your first playthrough, your karmic powers are locked after a certain point. However, you can change your karma as much as you want. If you want the good ending, you will need to start a new game.