Identify I can't remember

[RestlessZenza]

I may be butchering this so sorry in advance. I remember a game where you have two choices of types of monsters to train. If you choose one, you can basically smash the opponents monsters with a number of effects to help do so vs the other one is more pure hearted. I can't remember that game cause it's been so long. Anyone got any ideas? In addition, some monsters can posses the player to do interesting things. I can't remember the name.