Location: Mt. Moon

Method:
The first place you'll see these troublemakers is in Mt. Moon, where they're trying to steal fossils to sell. They mostly use weak Pokemon like Zubat and Rattata.

Location: Cerulean City

Method:
Two Rockets exist in Cerulean City. One is at the top of Nugget Bridge trying to make an offer you can't refuse, and the other has stolen a TM you'll need to retrieve at the house above Cerulean Gym (the former being only accessible after being said Gym). You'll get TM28 Dig for your troubles as well as passage to Vermilion City. The first Rocket uses Ekans and the second Drowzee, both troublesome in their own right.

More Rocket Grunts are in the areas surrounding Cerulean City. The first has set up a recruitment regiment on Nugget Bridge, and the other is hiding out in the backyard of the house he just robbed (after Misty is defeated). You will have to defeat both if you want to ride the S.S. Anne in Vermilion City..

Location: Celadon City

Method:
Celadon City has been overrun by Team Rocket with suspicious activity being linked to the Rocket Game Corner. Inside, a Rocket Grunt is idling by a poster on the back wall. Defeat him and you will be granted access to their secret hideout in the basement. Navigate the maze of warp panels on each floor, but be careful as they'll force you to move in one direction. You'll need to find the Lift Key on B4F to ride the elevator down on B3F to the Rocket Boss Giovanni's private office. There, you can fight him for the first time. If you defeat him, you receive the Silph Scope, which allows you to identify Ghost-type Pokemon.

The Rocket leader Giovanni fights with a fairly simple team the first time. All three of his monsters can be defeated with Fighting-type moves.

Location: Pokémon Tower

Method:
The Rockets killed a Cubone's mother in the Pokemon Tower and took Mr. Fuji hostage. Before you can get to the top floor, you must calm the angry ghost of the mother Marowak by defeating it in battle. You can't catch this Pokemon.After that, defeat the three Rockets and talk to Mr. Fuji to receive the Poke Flute..

Location: Saffron City

Method:
Saffron City is taken over by the Rockets, who block entry to homes as well as the local Pokemon Gym. After you beat Koga, the guard at Silph Co.'s office building will drift to sleep and you can enter to find Team Rocket staging a hostile takeover. To make things easy, head for the 5th level right away and get the Card Key at the bottom. From here you can open every door in the building and can avoid the pesky warp portals that will take you god knows where in the building. Take this to the 3rd floor and open the room on the center-left, taking the warp portal on the far left to gain access to a second warp portal that'll let you meet up with your rival on floor 7. After facing him, you'll have free access to a portal taking you to the president's room. Giovanni demands he turn over the Master Ball, which guarantees any Pokemon can be captured.

For the Rocket matches, many can be skipped. If you're a completionist though, be warned that they use Pokemon they haven't tried before. Magnemites, Cubones, and Voltorbs are used as well as Koffing, Raticate, and Golbat. Weezing, Arbok, Electrode, and Marowak might be hard to fight, so remember to open and use the healing room on floor 9 whenever you need to.

Giovanni's team is a bit more diverse, including Nidoqueen and Kangaskhan. After you defeat him, collect the last of the seven badges then go to Viridian City, where Giovanni has resumed his post as Gym Leader.

Location: Viridian City

Method:
Although the gym itself is not populated with Team Rocket members, this is the last place you meet Giovanni. He uses a team more centered around Ground-types, and you will receive the final badge along with other rewards once he's defeated. After the match he announces that he will be abandoning Team Rocket for good to dedicate himself to training. However, his team sees otherwise...which you will find out after beating the Pokemon League!

Location: Mt. Ember

Method:
Once you become Champion and acquire the National Dex, go to One Island to visit Celio. He will send on an errand to collect the Ruby that lays hidden in Mt. Ember. Unfortunately, some rogue Team Rocket members are also searching for it and will ambush you. Defeat them and find the Ruby inside. One of the grunts will even give the first password to their secret hideout on Five Island. Take the Ruby to Celio for your next instructions.

Location: Four Island

Method:
After Celio gives you the Rainbow Pass, take a trip to Four Island, home of the Elite Four member Lorelei. Find her in the Icefall Cave, where Rocket members are harassing local wild Pokemon. After you defeat them, Lorelei will thank you while the members flee to their base on Five Island.

Location: Five Island

Method:
The Rocket Warehouse was constructed in Five Island Meadow and remains their stronghold for the rest of the Sevii Islands arc. However, you can't enter it without both passwords. Continue onward searching for the Sapphire on Six Island and see if you can come across the other secret code.

Location: Dotted Hole

Method:
In the ancient ruins of Six Island, there is a chamber that requires you use Cut on the door to enter. Complete the puzzle by falling through the top hole, then the left, then right, then down. You will find the Sapphire on the bottom floor - but it seems you were followed! An agent working for Team Rocket will snatch the Sapphire from your hands then head off back to Five Island to sell it at the Rocket Warehouse. Before he leaves however he will give you the second password, enabling you to raid the outlet.

Location: Five Island / Rocket Warehouse

Method:
Now that you have both passwords you can defeat Team Rocket once and for all. In this secret hideout you will find Team Rocket up their usual nefarious tricks, including hoarding stolen Pokemon and researching how to force evolution. The puzzles in here are similar to the hideout in Celadon City and the Viridian City Gym. This time you'll fight two admins in lieu of Giovanni, as well as Gideon, who is hanging around with the Sapphire in his possession.The first Rocket Admin uses three Poison-types you've seen in other major battles from the game. Be careful though as her Pokemon have powerful movesets.After the path to the main office is switched on, you can fight the second Rocket Admin. His team is a bit different, using the Pokemon Houndoom as his main powerhouse. After being defeated, the Admin will recognize your Earth Badge and learn what's happened to Team Rocket.

After you've beaten Gideon, Team Rocket will be finished for good in the game. However, they return in the 2009 games Pokemon HeartGold and SoulSilver, so play those next to learn the true fate of Team Rocket.

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.