To defeat the Orc LOD, attack the two hammers on his sides first. It will slow him down and make him do only one attack instead of three. I would suggest leveling the green haired girl to max, as that is who I used to beat that fight.
To defeat the spider, use the purple girl.
I know the game is frustrating to understand right off the bat. I used the green, pink, and purple girls almost exclusively. Take a loss on purpose to look at the enemy pattern and determine which girl's pattern would best counter it. Doing so also unlocks it in the gallery after finishing the game.