The situation in Pokémon Tower is grave indeed, but with the Silph Scope, you should be able to dig up whatever is causing all the trouble. You don't have to do anything special with the scope, but just make sure you have it with you when you enter the tower. The Silph Scope automatically identifies ghosts and makes it possible to engage them in combat.
Into the Tower
Scoping out danger
Without the Silph Scope, you can't identify the ghosts lurking in Pokémon Tower, and therefore you can't fight them. With the scope in hand, you can fight and try to capture these astral aggressors. Note that Normal and Fighting-type moves don't affect Ghost-type Pokémon at all, so use caution in battle. You'll have better luck catching a Gastly or a Haunter if you use Great Balls instead of regular Poké Balls. You can also find some Cubones here too.
With the Silph Scope in your hot little hands, it's time to head back to Pokémon Tower and figure out what is going on. The quickest path (if you did not capture a Pokémon that can Fly after using HM02) is to go back to Route #7, hand the guard a frosty beverage to end the baffling "Thirsty Guard" crisis, and then cut through Saffron City on your way East to Lavender Town. On your way through Saffron City, you might just want to stop in at the Poké Mart and grab a Super or Max Repel. The Repel is for the Tower, where you'll be assaulted by Gastly, and occasionally Haunter.
Not this guy again...
Rival Battle #5
Pidgeotto Level 25
Fearow Level 25
//
Gyarados / Exeggcute / Growlithe Level 23
//
Shellder / Magnemite / Vulpix Level 23
//
Growlithe / Gyarados / Exeggcute Level 22
//
Vulpix / Shellder / Magnemite Level 22
Kadabra Level 20
Sandshrew Level 20
Stage 2 Starter Level 25
Eevee Level 25
When your rival gets in your way on the second floor, he'll pick a fight as usual. Like some of the previous battles, he isn't going to be that hard on you, so again you should have an easy time.
If you're playing the Red or Blue cartridge, he might have an alternate lineup (a level 25 Pidgeotto, a level 23 Gyarados/Exeggcute/Growlithe, a level 22 Growlithe/Gyarados/Exeggcute, a level 20 Kadabra, and the starter Pokémon he chose at the beginning of the game in it's first stage evolution). Gyarados is absent if you select Charmander, and your rival will have a level 23 Growlithe and a level 22 Exeggcute in his lineup. Exeggcute is absent if you select Squirtle, and your rival will have a level 23 Gyarados and a level 22 Growlithe in his lineup. Growlithe is absent if you select Bulbasaur, and your rival will have a level 23 Exeggcute and a level 22 Gyarados in his lineup.
In the Yellow game, he'll be a little more formidable. Besides his Fearow, Shellder, Magnemite and/or Vulpix and Sandshrew, your rival will also use his Eevee, which he will soon evolve into a Flareon, Vaporeon or Jolteon. Shellder is absent if your rival is going to evolve Eevee into Vaporeon, and your rival will have a level 23 Vulpix and a level 22 Magnemite in his lineup. Magnemite is absent if your rival is going to evolve Eevee into Jolteon, and your rival will have a level 23 Shellder and a level 22 Vulpix in his lineup. Vulpix is absent if your rival is going to evolve Eevee into Flareon, and your rival will have a level 23 Magnemite and a level 22 Shellder in his lineup.
To easily deal with the rival's Pokémon, use the following on him:
Electric attacks on the Gyarados (remember that it has a 4x weakness to them), Shellder, Wartortle, and the Flying-type Pokémon.
Ice attacks (the recently acquired Ice Beam is an great option) on Exeggcute, Ivysaur, Sandshrew, and the Flying-type Pokémon.
Water attacks on Growlithe, Vulpix, Charmeleon, and Sandshrew.
Ground type attacks on the Magemite and use powerful physical attacks on Kadabra. The Eevee can be dealt with by using anything you have.
Fighting Ghosts
Ghost-type Pokémon are completely invulnerable to Normal and Fighting moves, so many of your Pokémon's attacks will be useless here. Because of the only Ghost evolution line's secondary type, Poison, they are weak to Psychic and Ground-type moves. Anything that can use Dig, especially a speedy one like Diglett, can pretty much get an instant K.O due to the Gastly and Haunter's poor defense stats. Pokémon like Kadabra and Drowzee are very powerful too. If you don't want to deal with lots of random encounters, just pop open the Max Repel... after you catch a Gastly for yourself if you want. Many Channelers also lurk this tower, and they seem possessed.
1
Channeler
660
Gastly
LV23
2
Channeler
660
Gastly
LV22
3
Channeler
720
Gastly
LV24
A
Escape Rope
Pokémon Tower 3F encounters
Gastly
90%
90%
95%
Haunter
1%
1%
5%
Cubone
9%
9%
N/A
1
Channeler
690
Gastly
LV23
Gastly
LV23
2
Channeler
660
Gastly
LV22
3
Channeler
720
Gastly
LV24
A
Awakening
B
HP Up
C
Elixer
Pokémon Tower 4F encounters
Gastly
86%
86%
95%
Haunter
5%
5%
5%
Cubone
9%
9%
N/A
1
Channeler
660
Gastly
LV22
2
Channeler
720
Gastly
LV24
3
Channeler
660
Haunter
LV22
4
Channeler
690
Haunter
LV23
A
Nugget
Pokémon Tower 5F encounters
Gastly
86%
86%
90%
Haunter
5%
5%
5%
Cubone
9%
9%
5%
A chance for rest
The leader of the Channelers has broken free of the dark power that held her, and created a reusable healing zone on the 5th floor. Make sure you heal and save while you have the opportunity, since there are a number of surprises ahead. Move one step forward and three steps down from the stairs to snag a hidden Elixir. Elixirs restore 10 PP for all moves for the Pokémon it is used on.
1
Channeler
690
Gastly
LV23
Gastly
LV23
2
Channeler
660
Gastly
LV22
3
Channeler
720
Gastly
LV24
A
Awakening
B
HP Up
C
Elixer
Pokémon Tower 4F encounters
Gastly
86%
86%
95%
Haunter
5%
5%
5%
Cubone
9%
9%
N/A
1
Channeler
660
Gastly
LV22
2
Channeler
720
Gastly
LV24
3
Channeler
660
Haunter
LV22
4
Channeler
690
Haunter
LV23
A
Nugget
Pokémon Tower 5F encounters
Gastly
86%
86%
90%
Haunter
5%
5%
5%
Cubone
9%
9%
5%
Surprise, surprise
The first surprise is at the stairway to the top floor, where the Ghost that you needed the Silph Scope for finally reveals itself as a level 30 Marowak. Make sure you have some strong Pokémon for this fight! It should be a pretty easy battle if you have Water, Grass, or Ice attacks. You cannot catch this Pokémon, as it will dodge any Poké Ball you throw its way, even a Master Ball! There is also a glitch where you can use a Poké Doll on the Ghost so you won't have to use the Silph Scope to fight it at all, allowing you to completely skip the Rocket Hideout if you want.
Pokémon Tower 6F encounters
Gastly
85%
85%
90%
Haunter
6%
6%
5%
Cubone
9%
9%
5%
1
Channeler
660
Gastly
LV22
Gastly
LV22
Gastly
LV22
2
Channeler
720
Gastly
LV24
3
Channeler
720
Gastly
LV24
4
Ghost
-
Marowak
LV30
A
X Accuracy
B
Rare Candy
At the top
More non-Gastly foes await on the top floor and they're from Team Rocket. Red and Blue players have to go through three Rocket guards, while Yellow players just have to deal with a single visit from Jessie and James, the pair of losers that's been trailing you all along.
1
Rocket
750
Zubat
LV25
Zubat
LV25
Golbat
LV25
2
Rocket
780
Koffing
LV26
Drowzee
LV26
3
Rocket
690
Zubat
LV23
Rattata
LV23
Raticate
LV23
Zubat
LV23
4
Jessie & James
810
Meowth
LV27
Arbok
LV27
Weezing
LV27
Pokémon Tower 7F encounters
Gastly
75%
75%
90%
Haunter
15%
15%
5%
Cubone
10%
10%
5%
Prepare for trouble...make it double!
Didn't you just pummel these guys at the Game Corner? No sooner have you defeated the ghost guarding the 7th floor in the Yellow version than Jesse and James show up again, trying to keep you from talking to Mr. Fuji. Their Ekans and Koffing have evolved into Arbok and Weezing, but you should still win the battle easily if you have a Psychic or Ground-type Pokémon. They'll run away, but don't think for a second that you've seen the last of these two troublemakers!
Mr. Fuji
After you've bested the Rockets, you'll find the missing Mr. Fuji. He'll thank you for your efforts with dealing with the Marowak Ghost which was the dead mother of a child Cubone, and will reward you with a gift of a Poké Flute, which you can use to awaken any sleeping Pokémon, and which finally makes that Rest skill useful.
They're weak to the powerful Psychic and Ground-type attacks, but their Normal and Fighting-type immunities more than make up for that minor inconvenience. They have very good offensive stats with a great Special stat and a top-notch Speed stat. The Gastly evolution line is similar to the Abra line with Special sweeper qualities but weak defenses (Abra is slightly better as a sweeper but Gastly is a little more sturdy). Gastly evolves into Haunter at level 25 and it is required to trade Haunter to evolve into the amazing Gengar.
Gengar itself has a pretty good movepool. It learns useful status move such as Hypnosis and Confuse Ray while it can learn attacks such as Night Shade, Lick, and Dream Eater. Despite not so strong Ghost attacks, it also can learn useful special attacks such as Thunderbolt, Mega Drain, and Psychic.
As adorable as they are rare, Cubones are seen infrequently in Red and Blue and almost never in Yellow (although in that version only, they're also found in the Safari Zone).
The decent Ground-type skill Bone Club comes built in, but better attacks like Bonemerang and Thrash (which does heavy damage for 3-4 turns in a row, but confuses Cubone) don't come until higher levels. Cubone is better in Yellow, since he learns Headbutt at level 18!