Pokémon Pokopia: How to Unlock Mew – Slate Puzzle Guide

Mew is the last entry in the Pokémon Pokopia Pokédex, and it does not show up in the wild — you have to build it. The path trips people up because it hides behind a wall that looks like plain scenery, and because the final spawn needs one extra interaction most players walk away before doing.

The short version

• Collect all 27 unique Mysterious Slates. They drop at random from glowing spots you break with Rock Smash, and you can’t pull a duplicate until the full set is complete.
• Head to the Withered Wasteland, to the right (northeast) of the Pokémon Center near the Horsea Fountain.
• Break the back wall with Rock Smash, follow the underpass, smash the cracked rocks on the left, and take the staircase down to the mural chamber.
• Place all 27 slates on the Mysterious Mural. When it completes, a portal appears in front of it.
• Interact with the completed mural to spawn Mew. It registers as Pokédex #300 — no battle, no Poké Ball.

There is no separate boss fight, no capture sequence, and no “secret temple.” The Mew site is an unnamed hidden chamber reached by the staircase in the Withered Wasteland. If you have been hunting a labeled temple on the map, that is why you keep coming up empty.

What you need before you start

The Mew unlock is a late-game collectible puzzle, so the real prerequisite is map progress and the one ability everything hinges on: Rock Smash. You use it twice over — to break the glowing spots that drop slates, and to break the walls that open the chamber. No Rock Smash, no Mew.

• The Rock Smash ability
• Access to the Withered Wasteland
• All 27 Mysterious Slates (you can gather these as you go)
• Time to revisit cleared regions, because slate drops are randomized

Slate drops are random but non-duplicating: every slate you find is permanent progress, and the game will not waste a drop on a piece you already own until all 27 are in hand. That means brute-force coverage works — you never have to farm one spot hoping for a specific missing piece.

How to collect all 27 Mysterious Slates

This is the long stretch. Slates come from Rock Smash on glowing spots and breakable blocks scattered across the island, not from one dedicated dungeon. So treat it as a world sweep: hit every glowing or cracked node you pass, including in regions you already finished.

• Smash cracked rocks and glowing spots on sight, even in old areas.
• Sweep whole biomes per run instead of resetting one room.
• Keep every Mysterious Slate — you never discard them.
• Because drops don’t duplicate, efficiency comes from volume, not from re-checking the same node.

If you are not sure how many you still need, the mural is the fastest check: an incomplete mural means you are short, no matter how full your bag feels. While you are out sweeping for breakables, the same exploration habit pays off elsewhere on the island — see our item cloning guide for getting more out of what you collect.

Where the Mew chamber is

The mural chamber sits in the Withered Wasteland, to the right and northeast of the Pokémon Center, near the Horsea Fountain. The entrance is easy to miss because the key wall reads as normal scenery until you use Rock Smash on it.

• Go to the Withered Wasteland Pokémon Center and head northeast toward the Horsea Fountain.
• Find the breakable back wall and open it with Rock Smash.
• Follow the underpass inside.
• Break the cracked rocks on the left side.
• Descend the staircase to reach the mural chamber.

If you hit a dead end, you almost certainly missed one of the left-side cracked rocks. The chamber is tucked behind multiple breakable barriers and a staircase — breaking only the first wall does not get you to the puzzle.

How to solve the mural puzzle

This is a reconstruction puzzle, not a fight. Interact with the Mysterious Mural and slot every slate into place. As you add slates, the wall fills in; when the last correct piece lands, the mural completes into a clean grid and a portal appears in front of it. That portal is your confirmation the puzzle is solved.

• Interact with the mural after entering the chamber.
• Place the Mysterious Slates into their positions until all 27 are used.
• Watch for the completed grid and the portal effect at the front of the mural.

If the mural won’t complete, it is one of two things: you are still missing a slate, or you have not placed them all yet. The solved state is unmistakable — you should never have to guess whether it worked.

The exact step that spawns Mew

Once the mural is restored and the portal is up, interact with the completed mural again. This is the step people skip. Finishing the wall sets up the event; the extra interaction is what makes Mew emerge and registers it as Pokédex #300, the final entry. Solve the puzzle and immediately leave, and it will look like the game broke when really the trigger never fired.

The encounter has no gating beyond the puzzle. Mew’s listed conditions are Any time / Any weather, no battle — there is no time-of-day, weather, party-composition, or combat requirement.

• All 27 Mysterious Slates collected
• The correct Withered Wasteland chamber reached
• The mural fully restored (portal showing)
• The completed mural interacted with one more time

What happens after Mew appears

Mew is not battled or caught with a ball. It comes straight out of the completed mural and registers as Pokédex entry #300, the last one in the game. You can befriend it to have it live on your island, and its specialty is Teleport — so expect it to wander and teleport around rather than stand still. If it pops out and starts moving unpredictably, that is the intended behavior, not a failed unlock.

With Mew secured, your Pokédex is complete. If you are mopping up the rest of the island’s content, our Grisemer main quest guide and Collinangle cooking and forging guide cover the other major late-game threads.

Common mistakes

• Hunting for a named temple. The site is an unnamed hidden chamber in the Withered Wasteland, not a labeled map marker.
• Stopping at 26 slates. Mew will not spawn from a partial mural.
• Skipping the second interaction. After the mural completes, you still have to interact with it to trigger Mew.
• Expecting a capture battle. There is no fight and no ball — Mew emerges from the mural.
• Breaking only the first wall. The chamber is behind the left-side cracked rocks and the staircase, not the entry wall alone.
• Discarding slates. Keep every Mysterious Slate until the mural is finished.

Practical takeaway

Sweep the island with Rock Smash until you have all 27 Mysterious Slates, knowing drops are random and never duplicate. Then go right of the Withered Wasteland Pokémon Center near the Horsea Fountain, break through to the staircase, and complete the Mysterious Mural. Interact with the finished mural one more time and Mew (#300) appears — no battle, any time, any weather — ready to befriend as your final Pokédex entry.