The fire forest is the strongest forest of them all apart from the dark forest later in the game. the best side to choose for the fire forest is the earth side,their defense is best suited to tackle fire monsters, another tactic is to heal whenever possible to avoid a possiabillity you might lose. the bosses are some of the strongest.(some of the ugliest too.)but don't be fooled they can be beat because i've been through the whole game i'd know how to do it,but to be honest i don't know how you all play the game,i just give guidelines. you must heal in the battle whenever possible during battle who knows attack they'll choose it's mainly their signiture attack though.
all i'll say is give them HELL!!!!