Since I haven't explained this here yet, I'll do it now.
In pokemon, you go around catching and training pocket monsters so you can become an ultimate trainer, by defeating the top trainers in the country.
In terramon, you catch terrain monsters, and your on an adventure around the world just for fun, when you discover an evil scientist is going around reviving ancient terramon and using them to take over the world. As the only person who knows, you feel that you need to stop him. That is why you train your terramon.
I would appreciate it if people would not try to compare the two games, since I've dealt with this issue on the other forums I use.