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.
Find ALL the Golden Gears.
Meet the requirements to open the Mysterious Gate.
Find all of the hidden costumes.
Discover ALL the Locations.
Collect all the Explorer Medallions in Crystal Cavern.
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.
Collect 10 Explorer Medallions.
Collect all the Explorer Medallions in Cozy Canyon.
Find a hidden hat.
Visit the hidden planet.
Take a picture of the Master Explorer.
Discover the mysterious travelling merchant.
Purchase an item from the shop.
Kick a Bucket Head.
Sometimes, things don't always go as planned.
Do a triple jump.
Earn your first Explorer Medallion.
Hey, watch where you're rolling!