Oh, well...I'm guessing you're probably a trainer. Or a breeder, but it all depends on what stuff you got in your bag...but basically it's a normal thing for Pokemon here to fight each other in battles! It's like for sport, yaknow?

It's a little bit hard to explain, but once you do it, I think you'll get the hang of it. You need at least one Pokemon with you all the time, just incase you run into a wild Pokemon.