The villains in Pokemon Yellow are the members of Team Rocket, vile gangsters who want to make a profit by exploiting Pokemon. Their goals range from stealing fossils to resurrect powerful ancient Pokemon, to recruiting new blood at a set-up challenge on a bridge, to outright selling Pokemon via the Celadon City casino. Along the way you'll face three prominent members: Jessies and James, fought as a duo, and Giovanni, the nefarious leader of Team Rocket.
|Encounter 1 - Mt. Moon|
Location: Mt. Moon
The first place you'll see these troublemakers is in Mt. Moon, where they're trying to steal fossils to sell the valuable remains. They're fairly easy to beat in their first encounter as they mostly use weak Pokemon like Zubat and Rattata.
|Encounter 2 - Cerulean City|
Location: Cerulean City
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.
|Encounter 3 - Celadon City|
Location: Celadon City
Access the Rocket's secret base by fighting the lone Rocket at the back of the Game Corner and clicking the button under the poster he hides in front of. From there you'll gain passage to the basement hideout of the evil clan. You'll need to face several grunts and work through a maze of platforms that spin you around to access a Lift Key on BF4, then use that to ride the elevator on B3F back down to BF4 to face their boss Giovanni in the adjacent room. He'll drop the Silph Scope upon defeat, allowing you to proceed and confront Marowak's ghost in the Pokemon Tower. (hint: you can skip this entire dungeon by buying a Poke Doll in the Celadon Dept. Store and using that in the battle versus Marowak). As for the Rockets in the base, you'll see a lot of Poison-types like Ekans and Koffing, as well as more of the usual staples like Rattata (and its evolution, Raticate) and Drowzee and the newcomer Machop.
Just before Giovanni you have to fight this flamboyant pair again. Watch for Ekans' Glare, which will paralyze you, and send them blasting off with Ground-type moves like Dig. Meowth will Screech to cut your defense in half or use Pay Day which leaves behind a couple extra bucks after the battle for you to collect.
The Rocket leader Giovanni fights with a fairly simple team on his first go. All three of his monsters can be defeated with Fighting-type moves. If you don't have any, Grass-type and Water-type moves work wonders on his dual Rock/Ground-type Pokemon and will probably do a number on Persian as well.
|Encounter 4 - Lavender Town|
Location: Lavender Town
Rockets killed a Cubone's mother in the Pokemon Tower and took Mr. Fuji hostage so you'll have to beat the trio at the top to save him. The usual Raticates and Koffings are ever-present, as are more evolutions like Golbat.
|Encounter 5 - Silph Co.|
Location: Saffron City
The last time you will encounter a gang of Rockets will also be one of the most bothersome. Probably the single largest and most time consuming dungeon in the game, the Silph Co. building is a pain in the backside due in part to the sheer number of floors you'll have to traverse. The good news is you don't need to hit up every single one; in fact, you can skip most if you don't care about items or experience. 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 Giovanni's room above. Don't forget your free Lapras!For the Rocket matchs, many can be skipped. If you're a completionist though, be warned that they use a whack of Pokemon they haven't tried before. Magnemites, Cubones, and Voltorbs are in demand as are the usual 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.
The last battle with Jessie and James is totally unremarkable from the last three. Use the same tactics as usual for the final encounter.
Giovanni means business this time. His team is a bit more diversed, with Nidoqueen being his main powerhouse, but shouldn't be a problem if you're packing heat yourself. Psychic-types may be handy (or something that can learn the attack Psychic, like your new Lapras), and Water-types are always good. Persian won't be much more of a threat than last time, but be wary of Nidoqueen's impressive girth and Rhyhorn's trouncing power. This is your second and last time fighting him as Rocket boss: tune into the Gym Leader page for the showdown with Giovanni that comes after.