A good strategy before fighting a higher level opponent is to first take a look at their starters and organize your Guards accordingly with their strong points.
Quicker Game
Perform the following trick to skip the fighting scenes or speed up the game when you are fighting with PVP. Select your opponent and then press the 'Home' button of your iPhone. Doing this will return you to your desktop wall where you can then run the 'Pocket Summoner' again and choose another battle.