Here is the full list of all 25 Poi achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Beat the game in New Game+ mode.
Collect ALL the Explorer Medallions.
Find the legendary treasure.
Take a picture of ALL the creatures.
Meet the requirements to open the Mysterious Gate.
Discover ALL the Locations.
Collect all the Explorer Medallions in Crystal Cavern.
Find all of the hidden costumes.
Find ALL the Golden Gears.
Find ALL the Fossils.
Collect all the Explorer Medallions in Sinking Sands.
Collect all the Explorer Medallions in Mount Magma.
Rescue all the baby Pin Birds.
Visit the hidden planet.
Find a hidden hat.
Collect all the Explorer Medallions in Cozy Canyon.
Collect 10 Explorer Medallions.
Discover the mysterious travelling merchant.
Sometimes, things don't always go as planned.
Take a picture of the Master Explorer.
Purchase an item from the shop.
Kick a Bucket Head.
Do a triple jump.
Hey, watch where you're rolling!
Earn your first Explorer Medallion.