Do I need to play online over xbox live to save skill points in RE6

The player characters from each scenario will have their own partners which are controlled by either the computer AI or another human player via local or online multiplayer. When playing in single player, the player can allow another player to join in online at any time and inventories are now kept seperate from each other.

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So basically no you can't switch but if you're hardcore you could buy another PS3, hook it up the local network and with the 2nd character with your feet :P

If you turn on online mode, then you cannot pause the game. If you still play alone but online mode is turned on you still cannot pause the game. Before starting the game, just turn off all the online possibilities then you can pause game by pressing start.