Mt. Moon Pokémon Yellow · Dungeon
Mt. Moon is the cave between Route 3 and Route 4, reached after the Boulder Badge and the route east of Pewter City. It has three floors, plenty of Zubat and a lot of trainers, and ends with you heading out toward Cerulean City. In Yellow, Jessie and James turn up on the bottom floor once you have taken a fossil, and a Super Nerd guards the fossils.
- Wild Pokémon
- 5
- Items
- 12
- Trainers
- 12
Connects to: Route 4
Position on the Kanto town map
Wild Pokémon
1F
| Pokémon | Type | Lv. | Chance |
|---|---|---|---|
 Zubat | Poison | 6–11 | 74.2% |
 Geodude | RockGround | 10 | 20.3% |
 Sandshrew | Ground | 12 | 4.3% |
 Clefairy | Normal | 11 | 1.2% |
B1F
| Pokémon | Type | Lv. | Chance |
|---|---|---|---|
| Zubat | Poison | 8–11 | 64.8% |
| Geodude | RockGround | 10–11 | 19.5% |
 Paras | BugGrass | 9–11 | 10.2% |
| Clefairy | Normal | 10–12 | 5.5% |
B2F
| Pokémon | Type | Lv. | Chance |
|---|---|---|---|
| Zubat | Poison | 10–13 | 54.3% |
| Geodude | RockGround | 11 | 19.9% |
| Paras | BugGrass | 13 | 15.2% |
| Clefairy | Normal | 9–13 | 10.5% |
Grass, cave and surfing chances are the Generation I encounter slots (10 slots weighted 51, 51, 39, 25, 25, 25, 13, 13, 11 and 3 out of 256); the Super Rod picks from four slots weighted 102, 76, 51 and 27, the Good Rod is 50/50 and the Old Rod always hooks a level 5 Magikarp. Where to find every Pokémon.
Trainers
| Trainer | Pokémon | Prize | Where |
|---|---|---|---|
 Hiker | Geodude 10Geodude 10 Onix 10 | ₽350 | 1F |
 Youngster |  Rattata 10Rattata 10Zubat 10 | ₽150 | 1F |
 Lass |  Oddish 11 Bellsprout 11 | ₽165 | 1F |
 Super Nerd |  Magnemite 11 Voltorb 11 | ₽275 | 1F |
| Lass | Clefairy 14 | ₽210 | 1F |
 Bug Catcher |  Weedle 11 Kakuna 11 | ₽110 | 1F |
| Bug Catcher |  Caterpie 10 Metapod 10Caterpie 10 | ₽100 | 1F |
| Super Nerd |  Grimer 12Voltorb 12 Koffing 12 | ₽300 | B2F |
 Team Rocket Grunt | Sandshrew 11Rattata 11Zubat 11 | ₽330 | B2F |
| Team Rocket Grunt | Zubat 12 Ekans 12 | ₽360 | B2F |
| Team Rocket Grunt | Rattata 13Zubat 13 | ₽390 | B2F |
Prize money is the trainer class’s base amount times the level of their last Pokémon.
Items
| Item | How | Where |
|---|---|---|
| Potion | Item ball | 1F |
| Moon Stone | Item ball | 1F |
| Rare Candy | Item ball | 1F |
| Escape Rope | Item ball | 1F |
| Potion | Item ball | 1F |
| TM12 Water Gun | Item ball | 1F |
| HP Up | Item ball | B2F |
| TM01 Mega Punch | Item ball | B2F |
| Moon Stone | Hidden | B2F |
| Ether | Hidden | B2F |
| Dome Fossil | Gift Choose the Dome Fossil or the Helix Fossil after beating the Super Nerd; you can only take one | B2F |
| Helix Fossil | Gift Choose the Dome Fossil or the Helix Fossil after beating the Super Nerd; you can only take one | B2F |
Hidden items need the Itemfinder or a lucky press of A on the right tile.
Tips
- Beat the Super Nerd on B2F and choose either the Dome Fossil or the Helix Fossil; you can only take one, and you can revive it later in Cinnabar Island.
- The rare Clefairy can be caught, and there are two Moon Stones (one in a visible item ball on 1F, one hidden on B2F) for evolving it.
- Grab the Rare Candy, HP Up and TMs (Mega Punch, Water Gun); an Escape Rope and two Potions are on 1F as well.
- Jessie and James are fought on B2F, so heal beforehand and bring something good against Poison types.
- Zubat attack constantly, so carry Antidotes or use Repel while exploring.
Walkthrough: Part 3: Route 3, Mt. Moon and Cerulean City
More maps
FAQ
Which fossil should I pick in Mt. Moon in Pokémon Yellow?
Either one: the Dome Fossil becomes Kabuto and the Helix Fossil becomes Omanyte. You can only take one.
Can I catch Clefairy in Mt. Moon?
Yes, it is rare on each floor; the easiest way to improve your odds is to spend time on the lower floors.
Where are the Moon Stones?
One is in an item ball on 1F and one is hidden on B2F.
What Pokémon can you catch in Mt. Moon in Pokémon Yellow?
5 species: Zubat, Geodude, Sandshrew, Clefairy, Paras. The tables show levels and encounter chances from the game data.
What items are in Mt. Moon?
12, including Potion, Moon Stone, Rare Candy, Escape Rope, TM12 Water Gun, HP Up.
Sources & picture credits
- Mt. Moon (Bulbapedia)
- pret/pokeyellow (decompiled game data)
- Map: Mt_Moon_1F_RBY.png
- Map: Mt_Moon_B1F_RBY.png
- Map: Mt_Moon_B2F_RBY.png
- Town map: Kanto_Town_Map_RGBY.png
Guide text is original retrogameindex writing, checked against Bulbapedia and the game data. Wild Pokémon, encounter rates, items, trainers, gifts and shops come from the pret/pokeyellow decompilation of the English game (pret/pokeyellow e89ead154b). Maps and sprites © Nintendo / Creatures / GAME FREAK, archived from the Bulbagarden Archives (listed on the image gallery).