Instructions
Collect one Pokemon for every Pokemon on your Rival's team, giving you a total of six Pokemon. The Rival's team will have two normal types, one fire type, one water type, one grass type and one bug type. Your team should have two fighting type Pokemon, one water type, one grass type, one fire type and one rock type.
Train your Pokemon team by battling other trainers and wild Pokemon. As you defeat other Pokemon, your team will gain experience points and reach a higher level. Get your Pokemon to level 80 or above for the best chance of beating your rival.
Purchase as many full restores as you can afford. Full restore potions cure all status ailments and restores all health points of your Pokemon.
Travel to the Northeast Island on your map after you defeat the Elite Four. This section is called the "Battle Zone."
Walk to the front of the battle tower from the dock. Your Rival waits in front of the Battle Tower on Saturday and Sunday (he will not be at the Battle Tower during the week). Speak with him and a battle ensues.
Pit your Pokemon against your Rival's team to exploit their weaknesses. For example, his normal type Pokemon are weak against your fighting type Pokemon (consult your Pokedex before the battle to determine what Pokemon on his team falls into what elemental category). If he switches his Pokemon to try and get the upper-hand on battle, switch out your Pokemon as well to maintain your advantage.
Heal your Pokemon as necessary using your full restores as you battle. The full restores cannot revive your Pokemon after they faint, so you must use the full restore before your Pokemon reach that point.
Defeat your Rival a total of 2,000 times to open access to the Kanto region. Your Rival's Pokemon will increase in strength as you battle, so take breaks from your battles with him to further level your Pokemon. You can start a new battle with your Rival every few minutes, but heal your Pokemon between each battle.
Travel south on the map after your 2,000th victory over your Rival. The Kanto region is all the way south of the Shinnoh continent.