I just beat Pokemon emerald and got the national pokedex. apparently now I can catch roaming Pokemon. the thing is, I read that every time you enter a new area, the roaming Pokemon move to a new location. if that is the case, how am I supposed to know where to go or what to do to find a roaming Pokemon? do I need to just keep going in and out of an area until I get lucky, or is there some sort of tracking system?