The general things I found were that you needed to have some shield/heal, especially for the later enemies. Going in guns blazing would not do any good if the Crazy gets a +200 on you first turn. The physics/wind/water combo is probably second-best imo, but I usually opted for Archer/Druid/Paladin if I went that route, just so I didn't die immediately.
At least from my experience, it seemed the reason fire/thunder was so good was because it has the potential to do huge bursts of damage compared to the other combinations (although its fully possible I just never got lucky with other lineups)