Demon Hall is an interesting challenge to build a team for. Every three rounds, you are offered a chance to increase one of your stats by either 30%, 15%, or 3%. You can choose between Life, Defense, Attack, and Magic, and the amount increased is dependent on how well you perform in each of the stages. In contrast with your dragon team, where you want purely offensive characters, in Demon hall you have many more suitable combinations. The standard recommended team is 3 tanky characters in front, with 3 damage dealers in the back.
Because you have the choice every 3 stages on which stat you want to increase, a lot of players benefit from choosing only a SINGLE type of offense to focus on. Having more characters on your team who benefit from Magic causes the 30% Magic increase to be far more efficient than the 30% Attack increase, and vice versa. However, a balanced (half magic based, half attack based) team is also capable of making it far, but you depend far more on your random bonuses being able to power up your attacks equally.