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