If you have older games and access to another DS...this 'trick' can be done. In the old game go the day-care and put a ditto in. Try to get the 3 starter pokemon from the old game and lay eggs for all 3! Transfer the eggs to Heart Gold (or Soul Silver) and hatch eggs. If you chose a water pokemon to start the game, your rival will have 'grass'! So, when your eggs hatch...train up the fire pokemon. This will give you an advantage over the rival!