Location: Pallet Town

Method:
The first fight takes place right after obtaining your starter. Your rival will always choose the Pokemon with a type advantage over yours; however, since the only attacks either of you have at the beginning belong to the Normal-type, you have nothing to fear.

Location: Route 22

Method:
Left of Viridian City your rival will be training his starter and newly caught Pidgey; this remains applicable until you pick up your first badge. Though the fight should be easy enough with your starter, you can always pick up a Pikachu in Viridian Forest if you're having trouble.

Location: Cerulean City

Method:
On the way to the Sea Cottage on Route 25, your Rival will be waiting on Nugget Bridge for your challenge. Rather than helping Bill change back from being a Pokemon, your rival decides hanging out on the bridge is better use of his time. His team has expanded to include a Rattata and Abra; as well, his Pidgey has evolved into a Pidgeotto. Despite this, his starter remains in its first form. Abra is essentially useless as it is unevolved and only knows Teleport. It's handy to use turns against Abra to heal or switch your own Pokemon. After this match you'll receive the Fame Checker from your rival.

Location: SS Anne

Method:
Again, your rival feels battling you is a more worthy cause instead of helping someone in need, this time the sea captain. His starter has evolved now as has his Abra and Rattata. A more formidable team than before, the rival will use stronger moves and a bit more strategy to bring you down. Be wary of Kadabra's high Special Attack and Speed stats.

Location: Pokémon Tower

Method:
This is where rival's team really takes shape. By now his Raticate has left the party and been replaced with the second and third of the elemental trio he'll have in coming battles. Your team should be reasonably balanced and ready to handle Kadabra like last time as well as Pidgeotto and the starter. Watch out if your rival isn't using Squirtle however as Gyarados is quite powerful this early in the game.

Location: Silph Co.

Method:
By now the rival has given his Pokemon some decent moves and gotten the starter, Pidgeot, and Alakazam to their final forms. A good idea is to have an Electric-type on your team if you chose Bulbasaur at the start; the majority of his team will fall to a fast Thunderbolt. Get rid of Alakazam as soon as possible: Psybeam can wreck your team with its speed and precision or confuse you if you stay alive.

Location: Route 22

Method:
This match might be a little nostalgic if you didn't pass up on his second challenge earlier in the game. He's done a bit more searching in the Safari Zone and caught a Rhyhorn, which has good Attack and Defence but poor Speed and Special stats. This team is a good warm up for the Elite Four...and the champion after that.

Location: Indigo Plateau

Method:
Staying one step ahead the whole game, it seems your rival has gone and beaten the Elite Four before you could. He uses a very balanced team, incorporating many different elemental types as well as some strong moves. The best strategy is to repay him in kind with a balanced team of your own.

Location: Four Island

Method:
Though your rival won't battle you this time, he will encourage you to check around the island to see if you can meet a familiar face. He will also alert you to the existence of Eggs, which can be received at the local Day Care if the right conditions are in place.

Location: Six Island

Method:
If you go into the local Pokemon Center you will once again meet your rival, who has seen the entirety of the Sevii Islands. With that, he will announce he's returning to Kanto to train his team while he works on the Pokedex. Pay attention as there may be a Pokemon from the local area on his team when you meet next.

Location: Indigo Plateau

Method:
While travelling the Sevii Islands it seems that your rival has also spent time improving his team. His coverage is better than ever, adding two very strong Pokemon found in the islands to an already well-rounded group. This team is the highest-leveled in the game too, mind. Defeat him once more and you will have completed the postgame storyline for FireRed and LeafGreen.