I'd recommend obtaining fairy boosters. There's quite a number of fairy cards that get more powerful the more fairy cards you play in that booster set. Either Dark Fairy queen or fairy fire (though you'll need the particular fairy that adds more fairy fire to your deck) are entirely capable of defeating even the final boss. The light fairy side also has a powerful healing card that only gets more powerful the longer you play a match with a light fairy deck.
Also from what I recall easy actually isn't drastically easier than normal. I personally found the difficulty jump from easy to normal a let down.