There are many classifications of pokemon which are
- Heavy Infantry
- Air Force
- Longrange Infantry
The Storyline to Poke Wars is staged in the pokemon world in the year 1600, during the rennisance/medieval time setting. The types of pokemon are divided at this point, fire, steel, water, etc. They are fighting for the rule over the pokemon the war is so catastrophic that it results into the spliting of land into regions. This is also why you can find certain pokemon in only certain regions, depending on where they were stationed in the war when it happend.