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Pokémon Let's Go Mt. Moon and Helix and Dome fossils - available Pokémon, items and trainers

Our complete Pokémon Let's Go walkthrough and guide to your big adventure with Pikachu or Eevee.

Mt. Moon is the first proper 'dungeon' you'll encounter in Pokémon Let's Go, and the Helix and Dome fossils are what you can look forward to as a reward for getting to the other end. It follows on from Route 4 west in your quest through Pokémon Let's Go's main story.

Below, we'll cover any and all of the obtainable Pokémon, item locations, trainers and their squads that you might encounter in the area, as well as walking you through any key steps of the story along the way.

We've also opted to break out walkthrough pages down into sections, referring to each of your visits to a given location, seeing as you often backtrack or revisit various places in your quest to become Champion! Where applicable, we'll split our page into one section for each visit, and of course if there are any, clearly mark any spoilers, too!

For more like this, be it specific systems explainers or walkthrough pages on more locations, head back to our main Pokémon Let's Go walkthrough and guide hub.

On this page:

Pokémon Let's Go: Mt. Moon and the Helix and Dome fossils

As we mentioned above Mt. Moon is your first proper 'dungeon' in Pokémon Let's Go - by which we mean a proper, big, self-contained area with lots of Pokémon, trainers, and items to find along the way.

How to make it through Mt. Moon

The Mount has a couple of main levels - an entrance level, and the basement level - as well as connecting level that only ever has a couple of corridors on it joining the entrance and the one below, but still features wild Pokémon and the like as you pass through it.

Progressing out the other side is actually simple enough: there are three ladders on the entrance level. You want to take the one in the top left, which is accessed by going all the way to the right of the entrance level, up to the top, and then along the top all the way to the far left, where there's a Hiker in the middle of a crater and the man who'll give you Poké Balls in the top left corner.

This is the ladder to take to get to the Basement level, which is the way to the exit.

Take the ladder there down to the middle floor, which is an L-shaped corridor with a ladder at the far bottom-right end, and down from that ladder to the basement. You can then work your way through the basement - over to the far right, down to the bottom, and back up the left hand side - out up another ladder to a different, very short corridor on the middle floor, and up the nearby ladder there to the exit.

Use the other two ladders on the entrance level, meanwhile, to grab a couple more items in the other dead-end areas, and beat some more trainers, if you want to be a completionist.

Inside Mt. Moon

Head inside then, to find Jessie and James of Team Rocket waiting for you - looks like you snuck up on them while Meowth was sleeping on watch!

As you head round to the right you'll get a glimpse of Team Rocket again, and then more Team Rocket Grunts dotted around the place who'll battle you on sight - and won't offer any friendly Poké Balls as reward when you beat them. They are the bad guys, after all.

On the entrance level, the man in very top left by the Pearl will give you Poké Balls if you run low, which is handy.

After passing Team Rocket several times on the basement level, you'll finally reach a Super Nerd guarding two Fossils, towards the end of that main basement area.

Defeat him, and you'll get your pick of the two: the Dome Fossil or Helix Fossil, which represent Kabuto or Omanyte respectively! You can't do anything with these now, but all we'll say is once you reach Cinnabar Island much later in the game, you should probably visit the lab...

A battle with Jessie and James of Team Rocket awaits, and then after that just follow the path and the ladders ahead of you to exit!

Available Pokémon

This is a dead end, accessed via the second ladder on the entrance level - but it contains a hidden Moon Stone, a rare item. It reportedly respawns in this spot once per day.

Available Items

PotionTurn left as you enter and it's on the bottom end of the area
3x Poké BallsBug Catcher Kent
5x Great BallsTop left corner, heading left form the entrance, by Bug Catcher Kent
3x Poké BallsLass Evelyn
3x Poké BallsYoungster Toby
EtherBottom right of entrance level past Youngster Toby
3x Poké BallsSuper Nerd Jovan
AwakeningBy Super Nerd Jovan, to the right after the entrance
RepelFar right side of entrance level
Bag of StardustHidden, in small crater in top right of entrance level
3x Poké BallsLass Miriam
PearlVery top left of entrance level after working your way around from the back right
3x Poké BallsHiker Marcos
ReviveTop left of room after you descend from seeing Meowth.
PotionPast the first Team Rocket Grunt, just before you see Jessie and James tell Meowth to get the fossils
ReviveTo the right of red-haired Team Rocket Grunt
10x Poké BallsFrom the man who tops you up if you run out, top left of entrance level
NuggetTop back area of basement level
Rare CandyFrom basement level with single Team Rocket Grunt
Moon StoneHidden, in the small crater in the closed off upper part of the basement level. To get there, take the second ladder you encounter from the entrance level. Or, in a crater on the basement level accessed from the first ladder on the entrance level. They seem to rotate between the two locations!
Dome FossilChoice of either this or Helix Fossil after beating Super Nerd Miguel
Helix FossilChoice of either this or Dome Fossil after beating Super Nerd Miguel
Watch on YouTube

Head back to our main Pokémon Let's Go walkthrough and guide hub for all our pages in one place, including detailed, step-by-step help for tough spots like Cerulean Cave, and the Elite Four, plus tough dungeons like Silph Co., Seafoam Islands and Victory Road. Otherwise, take a peek(achu) at our Pokémon Let's Go TM list and all TM locations, Let's Go's starter locations and how to get Bulbasaur, Charmander and Squirtle, along with how to get Mew in Let's Go, and how to get Meltan in Let's Go and Go too. Beyond that we also explain how connect Pokémon Go to Let's Go on Nintendo Switch and transfer Pokémon, Catching, catch combos, and how to catch Pokémon, a quick collection of our best Pokémon Let's Go tips and tricks to get you off to a great start, and finally what we know about the Pokémon Pass app distribution event too.

Trainers and Battles

Trainer NamePokémonLevel
Bug Catcher KentButterfree7
Lass EvelynBellsprout8
Youngster TobyMankey8
Super Nerd JovanGrimer10
Lass MiriamClefairy8
Youngster JoshSandshrew8
Hiker MarcosGeodude
Team Rocket GruntDrowzee9
Team Rocket GruntZubat9
Team Rocket GruntRattata9

That's everything here for now, so continue on to Route 4 east for the next steps in your quest, or cycle back to our main Pokémon Let's Go walkthrough and guide hub for all the other pages we have like this.